World War I or the First World War (28 July 1914 – 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. It was fought between two coalitions, the Allies (primarily France, the United Kingdom, Russia, Italy, Japan, and the United States) and the Central Powers (led by Germany, Austria-Hungary, and the Ottoman Empire). Fighting occurred throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died as a result of genocide, while the 1918 Spanish flu pandemic was exacerbated by the movement of combatants during the war.

The first decade of the 20th century saw increasing diplomatic tension between the European great powers. This reached breaking point on 28 June 1914, when a Bosnian Serb named Gavrilo Princip assassinated Archduke Franz Ferdinand, heir to the Austro-Hungarian throne. Austria-Hungary held Serbia responsible, and declared war on 28 July. Russia came to Serbia's defence, and by 4 August, defensive alliances had drawn in Germany, France, and Britain.

German strategy in 1914 was to first defeat France, then attack Russia. However, this failed, and by the end of 1914, the Western Front consisted of a continuous line of trenches stretching from the English Channel to Switzerland. The Eastern Front was more fluid, but neither side could gain a decisive advantage, despite a series of costly offensives. Attempts by both sides to bypass the stalemate caused fighting to expand into the Middle East, the Alps, the Balkans, and overseas colonies, bringing Bulgaria, Romania, Greece, and others into the war.

The United States entered the war on the side of the Allies in April 1917, while the Bolsheviks seized power in the Russian October Revolution, and made peace with the Central Powers in early 1918. Freed from the Eastern Front, Germany launched an offensive in the west on March 1918, hoping to achieve a decisive victory before American troops arrived in significant numbers. Failure left the German Imperial Army exhausted and demoralised, and when the Allies took the offensive in August 1918, they could not stop the advance.

Between 29 September and 3 November 1918, Bulgaria, the Ottoman Empire, and Austria-Hungary agreed to armistices with the Allies, leaving Germany isolated. Facing revolution at home, and with his army on the verge of mutiny, Kaiser Wilhelm II abdicated on 9 November. The Armistice of 11 November 1918 brought the fighting to a close, while the Paris Peace Conference imposed various settlements on the defeated powers, the best-known being the Treaty of Versailles. The dissolution of the Russian, German, Austro-Hungarian, and Ottoman Empires resulted in the creation of new independent states, among them Poland, Czechoslovakia, and Yugoslavia. Failure to manage the instability that resulted from this upheaval during the interwar period contributed to the outbreak of World War II in September 1939.

The term world war was first coined in September 1914 by German biologist and philosopher Ernst Haeckel. He claimed that "there is no doubt that the course and character of the feared 'European War' ... will become the first world war in the full sense of the word,"[2] in The Indianapolis Star on 20 September 1914.

The term First World War (often abbreviated as WWI or WW1), had been used by Lt-Col. Charles à Court Repington, as a title for his memoirs (published in 1920); he had noted his discussion on the matter with a Major Johnstone of Harvard University in his diary entry of 10 September 1918.[3][4]

Prior to World War II, the events of 1914–1918 were generally known as the Great War or simply the World War.[5][6] In August 1914, The Independent magazine wrote "This is the Great War. It names itself".[7] In October 1914, the Canadian magazine Maclean's similarly wrote, "Some wars name themselves. This is the Great War."[8] Contemporary Europeans also referred to it as "the war to end war" and it was also described as "the war to end all wars" due to their perception of its then-unparalleled scale, devastation, and loss of life.[9] After World War II began in 1939, the terms became more standard, with British Empire historians, including Canadians, favouring "The First World War" and Americans "World War I".[10][failed verification]

For much of the 19th century, the major European powers maintained a tenuous balance of power among themselves, known as the Concert of Europe.[11] After 1848, this was challenged by a variety of factors, including Britain's withdrawal into so-called splendid isolation, the decline of the Ottoman Empire, New Imperialism, and the rise of Prussia under Otto von Bismarck. The 1866 Austro-Prussian War established Prussian hegemony in Germany, while victory in the 1870–1871 Franco-Prussian War allowed Bismarck to consolidate the German states into a German Empire under Prussian leadership. Avenging the defeat of 1871, or revanchism, and recovering the provinces of Alsace-Lorraine became the principal objects of French policy for the next forty years.[12]

In order to isolate France and avoid a war on two fronts, Bismarck negotiated the League of the Three Emperors (German: Dreikaiserbund) between Austria-Hungary, Russia and Germany. After Russian victory in the 1877–1878 Russo-Turkish War, the League was dissolved due to Austrian concerns over Russian influence in the Balkans, an area they considered of vital strategic interest. Germany and Austria-Hungary then formed the 1879 Dual Alliance, which became the Triple Alliance when Italy joined in 1882.[13] For Bismarck, the purpose of these agreements was to isolate France by ensuring the three Empires resolved any disputes between themselves; when this was threatened in 1880 by British and French attempts to negotiate directly with Russia, he reformed the League in 1881, which was renewed in 1883 and 1885. After the agreement lapsed in 1887, he replaced it with the Reinsurance Treaty, a secret agreement between Germany and Russia to remain neutral if either were attacked by France or Austria-Hungary.[14]

Bismarck viewed peace with Russia as the foundation of German foreign policy but after becoming Kaiser in 1890, Wilhelm II forced him to retire and was persuaded not to renew the Reinsurance Treaty by Leo von Caprivi, his new Chancellor.[15] This provided France an opportunity to counteract the Triple Alliance, by signing the Franco-Russian Alliance in 1894, followed by the 1904 Entente Cordiale with Britain, and the Triple Entente was completed by the 1907 Anglo-Russian Convention. While these were not formal alliances, by settling long-standing colonial disputes in Africa and Asia, British entry into any future conflict involving France or Russia became a possibility.[16] British and Russian support for France against Germany during the Agadir Crisis in 1911 reinforced their relationship and increased Anglo-German estrangement, deepening the divisions that would erupt in 1914.[17]

German industrial strength significantly increased after 1871, driven by the creation of a unified Reich, French indemnity payments, and the annexation of Alsace-Lorraine. Backed by Wilhelm II, Admiral Alfred von Tirpitz sought to use this growth in economic power to build a Kaiserliche Marine, or Imperial German Navy, which could compete with the British Royal Navy for world naval supremacy.[18] His thinking was influenced by US naval strategist Alfred Thayer Mahan, who argued possession of a blue-water navy was vital for global power projection; Tirpitz had his books translated into German, while Wilhelm made them required reading for his advisors and senior military personnel.[19]

However, it was also an emotional decision, driven by Wilhelm's simultaneous admiration for the Royal Navy and desire to outdo it. Bismarck calculated that Britain would not interfere in Europe so long as its maritime supremacy remained secure, but his dismissal in 1890 led to a change in policy and an Anglo-German naval arms race.[20] Despite the vast sums spent by Tirpitz, the launch of HMS Dreadnought in 1906 gave the British a technological advantage over their German rival which they never lost.[18] Ultimately, the race diverted huge resources into creating a German navy large enough to antagonise Britain, but not defeat it; in 1911, Chancellor Theobald von Bethmann Hollweg acknowledged defeat, leading to the Rüstungswende or 'armaments turning point', when he switched expenditure from the navy to the army.[21]

This decision was not driven by a reduction in political tensions, but German concern over Russia's recovery from defeat in the Russo-Japanese War and subsequent 1905 Russian Revolution. Economic reforms backed by French funding led to a significant post-1908 expansion of railways and infrastructure, particularly in its western border regions.[22] Since Germany and Austria-Hungary relied on faster mobilisation to compensate for their numerical inferiority compared to Russia, the threat posed by the closing of this gap was more important than competing with the Royal Navy. After Germany expanded its standing army by 170,000 troops in 1913, France extended compulsory military service from two to three years; similar measures were taken by the Balkan powers and Italy, which led to increased expenditure by the Ottomans and Austria-Hungary. Absolute figures are hard to calculate due to differences in categorising expenditure, since they often omit civilian infrastructure projects like railways which also had a military use. However, from 1908 to 1913, military spending by the six major European powers increased by over 50% in real terms.[23]

The years before 1914 were marked by a series of crises in the Balkans as other powers sought to benefit from Ottoman decline. While Pan-Slavic and Orthodox Russia considered itself the protector of Serbia and other Slav states, they preferred the strategically vital Bosporus straits to be controlled by a weak Ottoman government, rather than an ambitious Slav power like Bulgaria. Since Russia had its own ambitions in northeastern Anatolia and their clients had over-lapping claims in the Balkans, balancing these divided Russian policy-makers and added to regional instability.[24]

Austrian statesmen viewed the Balkans as essential for the continued existence of their Empire and Serbian expansion as a direct threat. The 1908–1909 Bosnian Crisis began when Austria annexed the former Ottoman territory of Bosnia and Herzegovina, which it had occupied since 1878. Timed to coincide with the Bulgarian Declaration of Independence from the Ottoman Empire, this unilateral action was denounced by the European powers, but accepted as there was no consensus on how to reverse it. Some historians see this as a significant escalation, ending any chance of Austria co-operating with Russia in the Balkans while damaging relations with Serbia and Italy, both of whom had their own expansionist ambitions in the region.[25]

Tensions increased after the 1911–1912 Italo-Turkish War demonstrated Ottoman weakness and led to the formation of the Balkan League, an alliance of Serbia, Bulgaria, Montenegro, and Greece.[26] The League quickly over-ran most of Ottoman Balkan territory in the 1912–1913 First Balkan War, much to the surprise of outside observers.[27] The Serbian capture of ports on the Adriatic resulted in partial Austrian mobilisation on 21 November 1912, including units along the Russian border in Galicia. In a meeting the next day, the Russian government decided not to mobilise in response, unwilling to precipitate a war for which they were not yet prepared.[28]

The Great Powers sought to re-assert control through the 1913 Treaty of London, which created an independent Albania, while enlarging the territories of Bulgaria, Serbia, Montenegro and Greece. However, disputes between the victors sparked the 33-day Second Balkan War, when Bulgaria attacked Serbia and Greece on 16 June 1913; it was defeated, losing most of Macedonia to Serbia and Greece, and Southern Dobruja to Romania.[29] The result was that even countries which benefited from the Balkan Wars, such as Serbia and Greece, felt cheated of their "rightful gains", while for Austria it demonstrated the apparent indifference with which other powers viewed their concerns, including Germany.[30] This complex mix of resentment, nationalism and insecurity helps explain why the pre-1914 Balkans became known as the "powder keg of Europe".[31]

On 28 June 1914, Archduke Franz Ferdinand of Austria, heir presumptive to Emperor Franz Joseph, visited Sarajevo, capital of the recently annexed provinces of Bosnia and Herzegovina. Six assassins[m] from the movement known as Young Bosnia, or Mlada Bosna, took up positions along the route taken by the Archduke's motorcade, with the intention of assassinating him. Supplied with arms by extremists within the Serbian Black Hand intelligence organisation, they hoped his death would free Bosnia from Austrian rule, although there was little agreement on what would replace it.[35]

Nedeljko Čabrinović threw a grenade at the Archduke's car and injured two of his aides, who were taken to hospital while the convoy carried on. The other assassins were also unsuccessful but an hour later, as Ferdinand was returning from visiting the injured officers, his car took a wrong turn into a street where Gavrilo Princip was standing. He stepped forward and fired two pistol shots, fatally wounding Ferdinand and his wife Sophie, who both died shortly thereafter.[36] Although Emperor Franz Joseph was shocked by the incident, political and personal differences meant the two men were not close; allegedly, his first reported comment was "A higher power has re-established the order which I, alas, could not preserve".[37]

According to historian Zbyněk Zeman, his reaction was reflected more broadly in Vienna, where "the event almost failed to make any impression whatsoever. On 28 and 29 June, the crowds listened to music and drank wine, as if nothing had happened."[38][39] Nevertheless, the impact of the murder of the heir to the throne was significant, and has been described by historian Christopher Clark as a "9/11 effect, a terrorist event charged with historic meaning, transforming the political chemistry in Vienna".[40]

The Austro-Hungarian authorities encouraged the subsequent anti-Serb riots in Sarajevo, in which Bosnian Croats and Bosniaks killed two Bosnian Serbs and damaged numerous Serb-owned buildings.[41][42] Violent actions against ethnic Serbs were also organised outside Sarajevo, in other cities in Austro-Hungarian-controlled Bosnia and Herzegovina, Croatia and Slovenia. Austro-Hungarian authorities in Bosnia and Herzegovina imprisoned and extradited approximately 5,500 prominent Serbs, 700 to 2,200 of whom died in prison. A further 460 Serbs were sentenced to death. A predominantly Bosniak special militia known as the Schutzkorps was established and carried out the persecution of Serbs.[43][44][45][46]

The assassination initiated the July Crisis, a month of diplomatic manoeuvring between Austria-Hungary, Germany, Russia, France and Britain. Believing Serbian intelligence helped organise Franz Ferdinand's murder, Austrian officials wanted to use the opportunity to end their interference in Bosnia and saw war as the best way of achieving this.[47] However, the Foreign Ministry had no solid proof of Serbian involvement and a dossier used to make its case was riddled with errors.[48] On 23 July, Austria delivered an ultimatum to Serbia, listing ten demands made intentionally unacceptable to provide an excuse for starting hostilities.[49]


Ethno-linguistic map of Austria-Hungary, 1910. Bosnia-Herzegovina was annexed in 1908.
Serbia ordered general mobilisation on 25 July, but accepted all the terms, except for those empowering Austrian representatives to suppress "subversive elements" inside Serbia, and take part in the investigation and trial of Serbians linked to the assassination.[50][51] Claiming this amounted to rejection, Austria broke off diplomatic relations and ordered partial mobilisation the next day; on 28 July, they declared war on Serbia and began shelling Belgrade. Having initiated war preparations on 25 July, Russia now ordered general mobilisation in support of Serbia on 30th.[52]

Anxious to ensure backing from the SPD political opposition by presenting Russia as the aggressor, Bethmann Hollweg delayed commencement of war preparations until 31 July.[53] That afternoon the Russian government were handed a note requiring them to "cease all war measures against Germany and Austria-Hungary" within 12 hours.[54] A further German demand for neutrality was refused by the French who ordered general mobilisation but delayed declaring war.[55] The German General Staff had long assumed they faced a war on two fronts; the Schlieffen Plan envisaged using 80% of the army to defeat France in the west, then switch to Russia. Since this required them to move quickly, mobilisation orders were issued that afternoon.[56]


Cheering crowds in London and Paris on the day war was declared.
At a meeting on 29 July, the British cabinet had narrowly decided its obligations to Belgium under the 1839 Treaty of London did not require it to oppose a German invasion with military force. However, this was largely driven by Prime Minister Asquith's desire to maintain unity; he and his senior Cabinet ministers were already committed to support France, the Royal Navy had been mobilised and public opinion was strongly in favour of intervention.[57] On 31 July, Britain sent notes to Germany and France, asking them to respect Belgian neutrality; France pledged to do so, Germany did not reply.[58]

Once the German ultimatum to Russia expired on the morning of 1 August, the two countries were at war. Later the same day, Wilhelm was informed by his ambassador in London, Prince Lichnowsky, that Britain would remain neutral if France was not attacked, and might not intervene at all given the ongoing Home Rule Crisis in Ireland.[59] Jubilant at this news, he ordered General Moltke, the German chief of staff, to "march the whole of the ... army to the East". This allegedly brought Moltke to the verge of a nervous breakdown, who protested that "it cannot be done. The deployment of millions cannot be improvised."[60] Lichnowsky soon realised he was mistaken, although Wilhelm insisted on waiting for a telegram from his cousin George V; once received it confirmed there had been a misunderstanding, and he told Moltke, "Now do what you want."[61]

Aware of German plans to attack through Belgium, French Commander-in-Chief Joseph Joffre asked his government for permission to cross the border and pre-empt such a move. To avoid a violation of Belgian neutrality, he was told any advance could come only after a German invasion.[62] On 2 August, Germany occupied Luxembourg and exchanged fire with French units; on 3 August, they declared war on France and demanded free passage across Belgium, which was refused. Early on the morning of 4 August, the Germans invaded and Albert I of Belgium called for assistance under the Treaty of London.[63][64] Britain sent Germany an ultimatum demanding they withdraw from Belgium; when this expired at midnight without a response, the two empires were at war.[65]

The strategy of the Central Powers suffered from miscommunication. Germany had promised to support Austria-Hungary's invasion of Serbia, but interpretations of what this meant differed. Previously tested deployment plans had been replaced early in 1914, but those had never been tested in exercises. Austro-Hungarian leaders believed Germany would cover its northern flank against Russia.[66] Germany, however, envisioned Austria-Hungary directing most of its troops against Russia, while Germany dealt with France. This confusion forced the Austro-Hungarian Army to divide its forces between the Russian and Serbian fronts.

Beginning on 12 August, the Austrian and Serbs clashed at the battles of the Cer and Kolubara; over the next two weeks, Austrian attacks were repulsed with heavy losses, dashing their hopes of a swift victory and marking the first major Allied victories of the war. As a result, Austria had to keep sizeable forces on the Serbian front, weakening its efforts against Russia.[67] Serbia's defeat of the 1914 invasion has been called one of the major upset victories of the twentieth century.[68] In spring 1915, the campaign saw the first use of anti-aircraft warfare after an Austrian plane was shot down with ground-to-air fire, as well as the first medical evacuation by the Serbian army in autumn 1915.[69][70]

Upon mobilisation in 1914, 80% of the German Army was located on the Western Front, with the remainder acting as a screening force in the East; officially titled Aufmarsch II West, it is better known as the Schlieffen Plan after its creator, Alfred von Schlieffen, head of the German General Staff from 1891 to 1906. Rather than a direct attack across their shared frontier, the German right wing would sweep through the Netherlands and Belgium, then swing south, encircling Paris and trapping the French army against the Swiss border. Schlieffen estimated this would take six weeks, after which the German army would transfer to the East and defeat the Russians.[71]

The plan was substantially modified by his successor, Helmuth von Moltke the Younger. Under Schlieffen, 85% of German forces in the west were assigned to the right wing, with the remainder holding along the frontier. By keeping his left wing deliberately weak, he hoped to lure the French into an offensive into the "lost provinces" of Alsace-Lorraine, which was in fact the strategy envisaged by their Plan XVII.[71] However, Moltke grew concerned the French might push too hard on his left flank and as the German Army increased in size from 1908 to 1914, he changed the allocation of forces between the two wings from 85:15 to 70:30.[72] He also considered Dutch neutrality essential for German trade and cancelled the incursion into the Netherlands, which meant any delays in Belgium threatened the entire viability of the plan.[73] Historian Richard Holmes argues these changes meant the right wing was not strong enough to achieve decisive success and thus led to unrealistic goals and timings.[74]


French bayonet charge during the Battle of the Frontiers; by the end of August, French casualties exceeded 260,000, including 75,000 dead.
The initial German advance in the West was very successful and by the end of August the Allied left, which included the British Expeditionary Force (BEF), was in full retreat. At the same time, the French offensive in Alsace-Lorraine was a disastrous failure, with casualties exceeding 260,000, including 27,000 killed on 22 August during the Battle of the Frontiers.[75] German planning provided broad strategic instructions, while allowing army commanders considerable freedom in carrying them out at the front; this worked well in 1866 and 1870 but in 1914, von Kluck used this freedom to disobey orders, opening a gap between the German armies as they closed on Paris.[76] The French and British exploited this gap to halt the German advance east of Paris at the First Battle of the Marne from 5 to 12 September and push the German forces back some 50 km (31 mi).

In 1911, the Russian Stavka had agreed with the French to attack Germany within fifteen days of mobilisation, ten days before the Germans had anticipated, although it meant the two Russian armies that entered East Prussia on 17 August did so without many of their support elements.[77] Although the Russian Second Army was effectively destroyed at the Battle of Tannenberg on 26–30 August, their advance caused the Germans to re-route their 8th Field Army from France to East Prussia, a factor in Allied victory on the Marne.[citation needed]

By the end of 1914, German troops held strong defensive positions inside France, controlled the bulk of France's domestic coalfields and had inflicted 230,000 more casualties than it lost itself. However, communications problems and questionable command decisions cost Germany the chance of a decisive outcome, while it had failed to achieve the primary objective of avoiding a long, two-front war.[78] As was apparent to a number of German leaders, this amounted to a strategic defeat; shortly after the Marne, Crown Prince Wilhelm told an American reporter; "We have lost the war. It will go on for a long time but lost it is already."[79]

On 30 August 1914, New Zealand occupied German Samoa, now the independent state of Samoa. On 11 September, the Australian Naval and Military Expeditionary Force landed on the island of New Britain, then part of German New Guinea. On 28 October, the German cruiser SMS Emden sank the Russian cruiser Zhemchug in the Battle of Penang. Japan declared war on Germany prior to seizing territories in the Pacific which later became the South Seas Mandate, as well as German Treaty ports on the Chinese Shandong peninsula at Tsingtao. After Vienna refused to withdraw its cruiser SMS Kaiserin Elisabeth from Tsingtao, Japan declared war on Austria-Hungary as well, and the ship was sunk at Tsingtao in November 1914.[80] Within a few months, Allied forces had seized all German territories in the Pacific, leaving only isolated commerce raiders and a few holdouts in New Guinea.[81][82]

Some of the first clashes of the war involved British, French, and German colonial forces in Africa. On 6–7 August, French and British troops invaded the German protectorate of Togoland and Kamerun. On 10 August, German forces in South-West Africa attacked South Africa; sporadic and fierce fighting continued for the rest of the war. The German colonial forces in German East Africa, led by Colonel Paul von Lettow-Vorbeck, fought a guerrilla warfare campaign during World War I and only surrendered two weeks after the armistice took effect in Europe.[83]

Prior to the war, Germany had attempted to use Indian nationalism and pan-Islamism to its advantage, a policy continued post-1914 by instigating uprisings in India, while the Niedermayer–Hentig Expedition urged Afghanistan to join the war on the side of Central Powers. However, contrary to British fears of a revolt in India, the outbreak of the war saw a reduction in nationalist activity.[84][85] This was largely because leaders from the Indian National Congress and other groups believed support for the British war effort would hasten Indian Home Rule, a promise allegedly made explicit in 1917 by Edwin Montagu, then Secretary of State for India.[86]

In 1914, the British Indian Army was larger than the British Army itself, and between 1914 and 1918 an estimated 1.3 million Indian soldiers and labourers served in Europe, Africa, and the Middle East, while the Government of India and their princely allies supplied large quantities of food, money, and ammunition. In all, 140,000 soldiers served on the Western Front and nearly 700,000 in the Middle East, with 47,746 killed and 65,126 wounded.[87] The suffering engendered by the war, as well as the failure of the British government to grant self-government to India after the end of hostilities, bred disillusionment and fuelled the campaign for full independence that would be led by Mahatma Gandhi and others.[88]

Pre-war military tactics that emphasised open warfare and the individual rifleman proved obsolete when confronted with conditions prevailing in 1914. Technological advances allowed the creation of strong defensive systems largely impervious to massed infantry advances, such as barbed wire, machine guns and above all far more powerful artillery, which dominated the battlefield and made crossing open ground extremely difficult.[89] Both sides struggled to develop tactics for breaching entrenched positions without suffering heavy casualties. In time, however, technology began to produce new offensive weapons, such as gas warfare and the tank.[90]

After the First Battle of the Marne in September 1914, Allied and German forces unsuccessfully tried to outflank each other, a series of manoeuvres later known as the "Race to the Sea". By the end of 1914, the opposing forces confronted each other along an uninterrupted line of entrenched positions from the Channel to the Swiss border.[91] Since the Germans were normally able to choose where to stand, they generally held the high ground, while their trenches tended to be better built; those constructed by the French and English were initially considered "temporary", only needed until an offensive would smash the German defences.[92] Both sides tried to break the stalemate using scientific and technological advances. On 22 April 1915, at the Second Battle of Ypres, the Germans (violating the Hague Convention) used chlorine gas for the first time on the Western Front. Several types of gas soon became widely used by both sides, and though it never proved a decisive, battle-winning weapon, it became one of the most-feared and best-remembered horrors of the war.[93][94]

Neither side proved able to deliver a decisive blow for the next two years. Throughout 1915–17, the British Empire and France suffered more casualties than Germany, because of both the strategic and tactical stances chosen by the sides. Strategically, while the Germans mounted only one major offensive, the Allies made several attempts to break through the German lines.


German casualties, the Somme 1916
In February 1916 the Germans attacked French defensive positions at the Battle of Verdun, lasting until December 1916. The Germans made initial gains, before French counter-attacks returned matters to near their starting point. Casualties were greater for the French, but the Germans bled heavily as well, with anywhere from 700,000[95] to 975,000[96] casualties suffered between the two combatants. Verdun became a symbol of French determination and self-sacrifice.[97]

The Battle of the Somme was an Anglo-French offensive of July to November 1916. The opening day on 1 July 1916 was the bloodiest single day in the history of the British Army, which suffered 57,470 casualties, including 19,240 dead. As a whole, the Somme offensive led to an estimated 420,000 British casualties, along with 200,000 French and 500,000 German.[98] Gun fire was not the only factor taking lives; the diseases that emerged in the trenches were a major killer on both sides. The living conditions made it so that countless diseases and infections occurred, such as trench foot, shell shock, blindness/burns from mustard gas, lice, trench fever, "cooties" (body lice) and the 'Spanish flu'.[99][unreliable source?]

At the start of the war, German cruisers were scattered across the globe, some of which were subsequently used to attack Allied merchant shipping. The British Royal Navy systematically hunted them down, though not without some embarrassment from its inability to protect Allied shipping. For example, the light cruiser SMS Emden, which was part of the German East Asia Squadron stationed at Qingdao, seized or sank 15 merchantmen, as well as a Russian cruiser and a French destroyer. Most of the squadron was returning to Germany when it sank two British armoured cruisers at the Battle of Coronel in November 1914, before being virtually destroyed at the Battle of the Falkland Islands in December. The SMS Dresden escaped with a few auxiliaries, but after the Battle of Más a Tierra, these too had either been destroyed or interned.[100]

Soon after the outbreak of hostilities, Britain began a naval blockade of Germany. The strategy proved effective, cutting off vital military and civilian supplies, although this blockade violated accepted international law codified by several international agreements of the past two centuries.[101] Britain mined international waters to prevent any ships from entering entire sections of ocean, causing danger to even neutral ships.[102] Since there was limited response to this tactic of the British, Germany expected a similar response to its unrestricted submarine warfare.[103]

The Battle of Jutland (German: Skagerrakschlacht, or "Battle of the Skagerrak") in May/June 1916 developed into the largest naval battle of the war. It was the only full-scale clash of battleships during the war, and one of the largest in history. The Kaiserliche Marine's High Seas Fleet, commanded by Vice Admiral Reinhard Scheer, fought the Royal Navy's Grand Fleet, led by Admiral Sir John Jellicoe. The engagement was a stand off, as the Germans were outmanoeuvred by the larger British fleet, but managed to escape and inflicted more damage to the British fleet than they received. Strategically, however, the British asserted their control of the sea, and the bulk of the German surface fleet remained confined to port for the duration of the war.[104]


U-155 exhibited near Tower Bridge in London, after the 1918 Armistice
German U-boats attempted to cut the supply lines between North America and Britain.[105] The nature of submarine warfare meant that attacks often came without warning, giving the crews of the merchant ships little hope of survival.[105][106] The United States launched a protest, and Germany changed its rules of engagement. After the sinking of the passenger ship RMS Lusitania in 1915, Germany promised not to target passenger liners, while Britain armed its merchant ships, placing them beyond the protection of the "cruiser rules", which demanded warning and movement of crews to "a place of safety" (a standard that lifeboats did not meet).[107] Finally, in early 1917, Germany adopted a policy of unrestricted submarine warfare, realising the Americans would eventually enter the war.[105][108] Germany sought to strangle Allied sea lanes before the United States could transport a large army overseas, but after initial successes eventually failed to do so.[105]

The U-boat threat lessened in 1917, when merchant ships began travelling in convoys, escorted by destroyers. This tactic made it difficult for U-boats to find targets, which significantly lessened losses; after the hydrophone and depth charges were introduced, accompanying destroyers could attack a submerged submarine with some hope of success. Convoys slowed the flow of supplies since ships had to wait as convoys were assembled. The solution to the delays was an extensive program of building new freighters. Troopships were too fast for the submarines and did not travel the North Atlantic in convoys.[109] The U-boats had sunk more than 5,000 Allied ships, at a cost of 199 submarines.[110]

World War I also saw the first use of aircraft carriers in combat, with HMS Furious launching Sopwith Camels in a successful raid against the Zeppelin hangars at Tondern in July 1918, as well as blimps for antisubmarine patrol.[111]

Faced with Russia in the east, Austria-Hungary could spare only one-third of its army to attack Serbia. After suffering heavy losses, the Austrians briefly occupied the Serbian capital, Belgrade. A Serbian counter-attack in the Battle of Kolubara succeeded in driving them from the country by the end of 1914. For the first ten months of 1915, Austria-Hungary used most of its military reserves to fight Italy. German and Austro-Hungarian diplomats, however, scored a coup by persuading Bulgaria to join the attack on Serbia.[113] The Austro-Hungarian provinces of Slovenia, Croatia and Bosnia provided troops for Austria-Hungary in the fight with Serbia, Russia and Italy. Montenegro allied itself with Serbia.[114]

Bulgaria declared war on Serbia on 14 October 1915 and joined in the attack by the Austro-Hungarian army under Mackensen's army of 250,000 that was already underway. Serbia was conquered in a little more than a month, as the Central Powers, now including Bulgaria, sent in 600,000 troops total. The Serbian army, fighting on two fronts and facing certain defeat, retreated into northern Albania. The Serbs suffered defeat in the Battle of Kosovo. Montenegro covered the Serbian retreat towards the Adriatic coast in the Battle of Mojkovac in 6–7 January 1916, but ultimately the Austrians also conquered Montenegro. The surviving Serbian soldiers were evacuated by ship to Greece.[115] After conquest, Serbia was divided between Austro-Hungary and Bulgaria.[116]

In late 1915, a Franco-British force landed at Salonica in Greece to offer assistance and to pressure its government to declare war against the Central Powers. However, the pro-German King Constantine I dismissed the pro-Allied government of Eleftherios Venizelos before the Allied expeditionary force arrived.[117] The friction between the King of Greece and the Allies continued to accumulate with the National Schism, which effectively divided Greece between regions still loyal to the king and the new provisional government of Venizelos in Salonica. After intense negotiations and an armed confrontation in Athens between Allied and royalist forces (an incident known as Noemvriana), the King of Greece resigned and his second son Alexander took his place; Greece officially joined the war on the side of the Allies in June 1917.

The Macedonian front was initially mostly static. French and Serbian forces retook limited areas of Macedonia by recapturing Bitola on 19 November 1916 following the costly Monastir offensive, which brought stabilisation of the front.[118]

Serbian and French troops finally made a breakthrough in September 1918 in the Vardar offensive, after most of the German and Austro-Hungarian troops had been withdrawn. The Bulgarians were defeated at the Battle of Dobro Pole, and by 25 September British and French troops had crossed the border into Bulgaria proper as the Bulgarian army collapsed. Bulgaria capitulated four days later, on 29 September 1918.[119] The German high command responded by despatching troops to hold the line, but these forces were far too weak to re-establish a front.[120]

The disappearance of the Macedonian front meant that the road to Budapest and Vienna was now opened to Allied forces. Hindenburg and Ludendorff concluded that the strategic and operational balance had now shifted decidedly against the Central Powers and, a day after the Bulgarian collapse, insisted on an immediate peace settlement.[121]

The Ottomans threatened Russia's Caucasian territories and Britain's communications with India via the Suez Canal. As the conflict progressed, the Ottoman Empire took advantage of the European powers' preoccupation with the war and conducted large-scale ethnic cleansing of the indigenous Armenian, Greek, and Assyrian Christian populations, known as the Armenian genocide, Greek genocide, and Assyrian genocide.[122][123][124]

The British and French opened overseas fronts with the Gallipoli (1915) and Mesopotamian campaigns (1914). In Gallipoli, the Ottoman Empire successfully repelled the British, French, and Australian and New Zealand Army Corps (ANZACs). In Mesopotamia, by contrast, after the defeat of the British defenders in the siege of Kut by the Ottomans (1915–16), British Imperial forces reorganised and captured Baghdad in March 1917. The British were aided in Mesopotamia by local Arab and Assyrian fighters, while the Ottomans employed local Kurdish and Turcoman tribes.[125]


Italian Bersaglieri with a machine-gun instructor in Palestine
Further to the west, the Suez Canal was defended from Ottoman attacks in 1915 and 1916; in August, a German and Ottoman force was defeated at the Battle of Romani by the ANZAC Mounted Division and the 52nd (Lowland) Infantry Division. Following this victory, an Egyptian Expeditionary Force advanced across the Sinai Peninsula, pushing Ottoman forces back in the Battle of Magdhaba in December and the Battle of Rafa on the border between the Egyptian Sinai and Ottoman Palestine in January 1917.[126]

Russian armies generally had success in the Caucasus campaign. Enver Pasha, supreme commander of the Ottoman armed forces, was ambitious and dreamed of re-conquering central Asia and areas that had been lost to Russia previously. He was, however, a poor commander.[127] He launched an offensive against the Russians in the Caucasus in December 1914 with 100,000 troops, insisting on a frontal attack against mountainous Russian positions in winter. He lost 86% of his force at the Battle of Sarikamish.[128]


Kaiser Wilhelm II inspecting Turkish troops of the 15th Corps in East Galicia, Austria-Hungary (now Poland). Prince Leopold of Bavaria, the Supreme Commander of the German Army on the Eastern Front, is second from the left.
The Ottoman Empire, with German support, invaded Persia (modern Iran) in December 1914 in an effort to cut off British and Russian access to petroleum reservoirs around Baku near the Caspian Sea.[129] Persia, ostensibly neutral, had long been under the spheres of British and Russian influence. The Ottomans and Germans were aided by Kurdish and Azeri forces, together with a large number of major Iranian tribes, such as the Qashqai, Tangistanis, Lurs, and Khamseh, while the Russians and British had the support of Armenian and Assyrian forces. The Persian campaign was to last until 1918 and end in failure for the Ottomans and their allies. However, the Russian withdrawal from the war in 1917 led to Armenian and Assyrian forces, who had hitherto inflicted a series of defeats upon the forces of the Ottomans and their allies, being cut off from supply lines, outnumbered, outgunned and isolated, forcing them to fight and flee towards British lines in northern Mesopotamia.[130]


Russian forest trench at the Battle of Sarikamish, 1914–1915
General Yudenich, the Russian commander from 1915 to 1916, drove the Turks out of most of the southern Caucasus with a string of victories.[128] During the 1916 campaign, the Russians defeated the Turks in the Erzurum offensive, also occupying Trabzon. In 1917, Russian Grand Duke Nicholas assumed command of the Caucasus front. Nicholas planned a railway from Russian Georgia to the conquered territories so that fresh supplies could be brought up for a new offensive in 1917. However, in March 1917 (February in the pre-revolutionary Russian calendar), the Tsar abdicated in the course of the February Revolution, and the Russian Caucasus Army began to fall apart.

The Arab Revolt, instigated by the Arab bureau of the British Foreign Office, started June 1916 with the Battle of Mecca, led by Sharif Hussein of Mecca, and ended with the Ottoman surrender of Damascus. Fakhri Pasha, the Ottoman commander of Medina, resisted for more than two and half years during the siege of Medina before surrendering in January 1919.[131]

The Senussi tribe, along the border of Italian Libya and British Egypt, incited and armed by the Turks, waged a small-scale guerrilla war against Allied troops. The British were forced to dispatch 12,000 troops to oppose them in the Senussi campaign. Their rebellion was finally crushed in mid-1916.[132]

Total Allied casualties on the Ottoman fronts amounted 650,000 men. Total Ottoman casualties were 725,000, with 325,000 dead and 400,000 wounded.[133]

Although Italy joined the Triple Alliance in 1882, a treaty with its traditional Austrian enemy was so controversial that subsequent governments denied its existence and the terms were only made public in 1915.[134] This arose from nationalist designs on Austro-Hungarian territory in Trentino, the Austrian Littoral, Rijeka and Dalmatia, which were considered vital to secure the borders established in 1866.[135] In 1902, Rome secretly agreed with France to remain neutral if the latter was attacked by Germany, effectively nullifying its role in the Triple Alliance.[136]


Italian soldiers in trench, 1918

Austro-Hungarian trench at 3,850 metres in the Ortler Alps, one of the most challenging fronts of the war
When the war began in 1914, Italy argued the Triple Alliance was defensive in nature and it was not obliged to support an Austrian attack on Serbia. Opposition to joining the Central Powers increased when Turkey became a member in September, since in 1911 Italy had occupied Ottoman possessions in Libya and the Dodecanese islands.[137] To secure Italian neutrality, the Central Powers offered them the French protectorate of Tunisia, while in return for an immediate entry into the war, the Allies agreed to their demands for Austrian territory and sovereignty over the Dodecanese.[138] Although they remained secret, these provisions were incorporated into the April 1915 Treaty of London; Italy joined the Triple Entente and on 23 May declared war on Austria-Hungary,[139] followed by Germany fifteen months later.

The pre-1914 Italian army was the weakest in Europe, short of officers, trained men, adequate transport and modern weapons; by April 1915, some of these deficiencies had been remedied but it was still unprepared for the major offensive required by the Treaty of London.[140] The advantage of superior numbers was offset by the difficult terrain; much of the fighting took place at altitudes of over 3000 metres in the Alps and Dolomites, where trench lines had to be cut through rock and ice and keeping troops supplied was a major challenge. These issues were exacerbated by unimaginative strategies and tactics.[141] Between 1915 and 1917, the Italian commander, Luigi Cadorna, undertook a series of frontal assaults along the Isonzo which made little progress and cost many lives; by the end of the war, total Italian combat deaths totalled around 548,000.[142]

In the spring of 1916, the Austro-Hungarians counterattacked in Asiago in the Strafexpedition, but made little progress and were pushed by the Italians back to the Tyrol.[143] Although an Italian corps occupied southern Albania in May 1916, their main focus was the Isonzo front which after the capture of Gorizia in August 1916 remained static until October 1917. After a combined Austro-German force won a major victory at Caporetto, Cadorna was replaced by Armando Diaz who retreated more than 100 kilometres (62 mi) before holding positions along the Piave River.[144] A second Austrian offensive was repulsed in June 1918 and by October it was clear the Central Powers had lost the war. On 24 October, Diaz launched the Battle of Vittorio Veneto and initially met stubborn resistance, [145] but with Austria-Hungary collapsing, Hungarian divisions in Italy now demanded they be sent home.[146] When this was granted, many others followed and the Imperial army disintegrated, the Italians taking over 300,000 prisoners.[147] On 3 November, the Armistice of Villa Giusti ended hostilities between Austria-Hungary and Italy which occupied Trieste and areas along the Adriatic Sea awarded to it in 1915.[148]

Despite secretly agreeing to support the Triple Alliance in 1883, Romania increasingly found itself at odds with the Central Powers over their support for Bulgaria in the 1912 to 1913 Balkan Wars and the status of ethnic Romanian communities in Hungarian-controlled Transylvania,[149] which comprised an estimated 2.8 million of the 5.0 million population.[150] With the ruling elite split into pro-German and pro-Entente factions, Romania remained neutral in 1914, arguing like Italy that because Austria-Hungary had declared war on Serbia, it was under no obligation to join them.[151] They maintained this position for the next two years, while allowing Germany and Austria to transport military supplies and advisors across Romanian territory.[152]

In September 1914, Russia had acknowledged Romanian rights to Austro-Hungarian territories including Transylvania and Banat, whose acquisition had widespread popular support, [150] and Russian success against Austria led Romania to join the Entente in the August 1916 Treaty of Bucharest.[152] Under the strategic plan known as Hypothesis Z, the Romanian army planned an offensive into Transylvania, while defending Southern Dobruja and Giurgiu against a possible Bulgarian counterattack.[153] On 27 August 1916, they attacked Transylvania and occupied substantial parts of the province before being driven back by the recently formed German 9th Army, led by former Chief of Staff Falkenhayn.[154] A combined German-Bulgarian-Turkish offensive captured Dobruja and Giurgiu, although the bulk of the Romanian army managed to escape encirclement and retreated to Bucharest, which surrendered to the Central Powers on 6 December 1916.[155]

Approximately 16% of the pre-war Austro-Hungarian population consisted of ethnic Romanians, whose loyalty faded as the war progressed; by 1917, they made up more than 50% of the 300,000 deserters from the Imperial army.[156] Prisoners of war held by the Russian Empire formed the Romanian Volunteer Corps who were repatriated to Romania in 1917.[157][158][n] Many fought in the battles of Mărăști, Mărășești and Oituz, where with Russian support the Romanian army managed to defeat an offensive by the Central Powers and even take back some territory.[161] Left isolated after the October Revolution forced Russia out of the war, Romania signed an armistice on 9 December 1917.[162] Shortly afterwards, fighting broke out in the adjacent Russian territory of Bessarabia between Bolsheviks and Romanian nationalists, who requested military assistance from their compatriots. Following their intervention, the independent Moldavian Democratic Republic was formed in February 1918, which voted for union with Romania on 27 March.[163]


Romanian troops during the Battle of Mărășești, 1917
On 7 May 1918 Romania signed the Treaty of Bucharest with the Central Powers, which recognised Romanian sovereignty over Bessarabia in return for ceding control of passes in the Carpathian Mountains to Austria-Hungary and granting oil concessions to Germany.[164] Although approved by Parliament, Ferdinand I refused to sign the treaty, hoping for an Allied victory; Romania re-entered the war on 10 November 1918 on the side of the Allies and the Treaty of Bucharest was formally annulled by the Armistice of 11 November 1918.[165][o] Between 1914 and 1918, an estimated 400,000 to 600,000 ethnic Romanians served with the Austro-Hungarian army, of whom up to 150,000 were killed in action; total military and civilian deaths within contemporary Romanian borders are estimated at 748,000.[167]

As previously agreed with France, Russian plans at the start of the war were to simultaneously advance into Austrian Galicia and East Prussia as soon as possible. Although their attack on Galicia was largely successful, and the invasions achieved their aim of forcing Germany to divert troops from the Western Front, the speed of mobilisation meant they did so without much of their heavy equipment and support functions. These weaknesses contributed to Russian defeats at Tannenberg and the Masurian Lakes in August and September 1914, forcing them to withdraw from East Prussia with heavy losses.[168][169] By spring 1915, they had also retreated from Galicia, and the May 1915 Gorlice–Tarnów offensive then allowed the Central Powers to invade Russian-occupied Poland.[170] On 5 August, the loss of Warsaw forced the Russians to abandon their Polish territories.

Despite the successful June 1916 Brusilov offensive against the Austrians in eastern Galicia,[171] shortages of supplies, heavy losses and command failures prevented the Russians from fully exploiting their victory. However, it was one of the most significant and impactful offensives of the war, diverting German resources from Verdun, relieving Austro-Hungarian pressure on the Italians, and convincing Romania to enter the war on the side of the Allies on 27 August. It also fatally weakened both the Austrian and Russian armies, whose offensive capabilities were badly affected by their losses and increased the disillusionment with the war that ultimately led to the Russian revolutions.[172]

Meanwhile, unrest grew in Russia as the Tsar remained at the front, with the home front controlled by Empress Alexandra. Her increasingly incompetent rule and food shortages in urban areas led to widespread protests and the murder of her favourite, Grigori Rasputin, at the end of 1916.[citation needed]

On 12 December 1916, after ten brutal months of the Battle of Verdun and a successful offensive against Romania, Germany attempted to negotiate a peace with the Allies.[173] However, this attempt was rejected out of hand as a "duplicitous war ruse".[173]

Soon after, US president Woodrow Wilson attempted to intervene as a peacemaker, asking in a note for both sides to state their demands and start negotiations. Lloyd George's War Cabinet considered the German offer to be a ploy to create divisions amongst the Allies. After initial outrage and much deliberation, they took Wilson's note as a separate effort, signalling that the United States was on the verge of entering the war against Germany following the "submarine outrages". While the Allies debated a response to Wilson's offer, the Germans chose to rebuff it in favour of "a direct exchange of views". Learning of the German response, the Allied governments were free to make clear demands in their response of 14 January. They sought restoration of damages, the evacuation of occupied territories, reparations for France, Russia and Romania, and a recognition of the principle of nationalities.[174] This included the liberation of Italians, Slavs, Romanians, Czecho-Slovaks, and the creation of a "free and united Poland".[174] On the question of security, the Allies sought guarantees that would prevent or limit future wars, complete with sanctions, as a condition of any peace settlement.[175] The negotiations failed and the Entente powers rejected the German offer on the grounds that Germany had not put forward any specific proposals.

By the end of 1916, Russian casualties totalled nearly five million killed, wounded or captured, with major urban areas affected by food shortages and high prices. In March 1917, Tsar Nicholas ordered the military to forcibly suppress a wave of strikes in Petrograd but the troops refused to fire on the crowds.[176] Revolutionaries set up the Petrograd Soviet and fearing a left-wing takeover, the State Duma forced Nicholas to abdicate and established the Russian Provisional Government, which confirmed Russia's willingness to continue the war. However, the Petrograd Soviet refused to disband, creating competing power centres and caused confusion and chaos, with frontline soldiers becoming increasingly demoralised and unwilling to fight on.[177]

In the summer of 1917 a Central Powers offensive began in Romania under the command of August von Mackensen to knock Romania out of the war. Resulting in the battles of Oituz, Mărăști and Mărășești where up to 1,000,000 Central Powers troops were present. The battles lasted from 22 July to 3 September and eventually the Romanian army was victorious. August von Mackensen could not plan for another offensive as he had to transfer troops to the Italian Front.[178]

Following the Tsar's abdication, Vladimir Lenin—with the help of the German government—was ushered by train from Switzerland into Russia on 16 April 1917. Discontent and the weaknesses of the Provisional Government led to a rise in the popularity of the Bolshevik Party, led by Lenin, which demanded an immediate end to the war. The Revolution of November was followed in December by an armistice and negotiations with Germany. At first, the Bolsheviks refused the German terms, but when German troops began marching across Ukraine unopposed, the new government acceded to the Treaty of Brest-Litovsk on 3 March 1918. The treaty ceded vast territories, including Finland, Estonia, Latvia, Lithuania, parts of Poland and Ukraine to the Central Powers.[179] Despite this enormous German success, the manpower required by the Germans to occupy the captured territory may have contributed to the failure of their Spring Offensive, and secured relatively little food or other materiel for the Central Powers war effort.

With the Russian Empire out of the war, Romania found itself alone on the Eastern Front and signed the Treaty of Bucharest with the Central Powers in May 1918, ending the state of war between Romania and the Central Powers. Under the terms of the treaty, Romania had to give territory to Austria-Hungary and Bulgaria, and lease its oil reserves to Germany. However, the terms also included the Central Powers recognition of the union of Bessarabia with Romania.[180][181]

The United States was a major supplier of war materiel to the Allies but remained neutral in 1914; many opposed the idea of involvement in "foreign wars", while German Americans made up over 10% of the total population in 1913.[182] On 7 May 1915, 128 Americans died when the British Passenger ship Lusitania was sunk by a German submarine. President Woodrow Wilson demanded an apology and warned the United States would not tolerate unrestricted submarine warfare but refused to be drawn into the war.[183] When more Americans died after the sinking of SS Arabic in August, Bethman-Hollweg ordered an end to such attacks.[184] Wilson argued he was "too proud to fight", although former president Theodore Roosevelt denounced the idea of "setting a spiritual example [to others] by sitting idle, uttering cheap platitudes and picking up their trade".[185] Despite growing pro-war sentiment, Wilson was narrowly re-elected as president in 1916.[186]

By the end of 1916, the British naval blockade was causing serious shortages in Germany and Wilhelm approved the resumption of unrestricted submarine warfare

on 1 February 1917.[188] While the German government recognised this action was likely to bring America into the war, the navy claimed they could starve Britain into submission in less than six months.[189] The military position also appeared stable, at least for the foreseeable future. Despite heavy losses at Verdun and the Somme during 1916, withdrawal to the newly created Hindenburg Line would enable the Westheer to conserve its troops, while it was clear Russia was on the brink of revolution. The combination meant Germany was willing to gamble it could force the Allies to make peace before the US could intervene in any meaningful way.[190]

Although Wilson severed diplomatic relations on 2 February, he was reluctant to start hostilities without overwhelming public support. On 24 February, he was presented with the Zimmermann Telegram; drafted in January by German Foreign Secretary Arthur Zimmermann, it was intercepted and decoded by British intelligence, who shared it with their American counterparts. Already financing Russian Bolsheviks and anti-British Irish nationalists, Zimmermann hoped to exploit nationalist feelings in Mexico caused by American incursions during the Pancho Villa Expedition. He promised President Carranza support for a war against the United States and help in recovering Texas, New Mexico, and Arizona, although this offer was promptly rejected.[191] Publication of the telegram on 1 March caused an upsurge in support for war but this quickly subsided.[187]


The Allied Avenue, 1917 painting by Childe Hassam, that depicts Manhattan's Fifth Avenue decorated with flags from Allied nations
The most significant factor in creating the support Wilson needed was the German submarine offensive, which not only cost American lives, but paralysed trade as ships were reluctant to put to sea. This caused food shortages in cities along the East Coast and on 22 March, Congress approved the arming of merchant ships.[192] Now committed to war, in his speech to Congress on 2 April Wilson presented it as a crusade "against human greed and folly, against Germany, and for justice, peace and civilisation".[193] On 6 April, Congress declared war on Germany as an "Associated Power" of the Allies.[194] At this stage they were not at war with the other Central Powers.[187]

The United States Navy sent a battleship group to Scapa Flow to join the Grand Fleet and provided convoy escorts. In April 1917, the United States Army had fewer than 300,000 men, including National Guard units, compared to British and French armies of 4.1 and 8.3 million respectively. The Selective Service Act of 1917 drafted 2.8 million men, although training and equipping such numbers was a huge logistical challenge. By June 1918, over 667,000 members of the American Expeditionary Forces, or AEF, had been transported to France, a figure which reached 2 million by the end of November.[195] However, American tactical doctrine was still based on pre-1914 principles, a world away from the combined arms approach used by the French and British in 1918.[196] US commanders were initially slow to accept such ideas, leading to heavy casualties and it was not until the last month of the war that these failings were rectified.[197]

Despite his conviction Germany must be defeated, Wilson went to war to ensure the US played a leading role in shaping the peace, which meant preserving the AEF as a separate military force, rather than being absorbed into British or French units as his Allies wanted.[198] He was strongly supported by AEF commander General John J. Pershing, a proponent of pre-1914 "open warfare" who considered the French and British emphasis on artillery as misguided and incompatible with American "offensive spirit".[199] Much to the frustration of his Allies, who had suffered heavy losses in 1917, he insisted on retaining control of American troops and refused to commit them to the front line until able to operate as independent units. As a result, the first significant US involvement was the Meuse–Argonne offensive in late September 1918.[200]

Verdun cost the French nearly 400,000 casualties, while the horrific conditions severely impacted morale, leading to a number of incidents of indiscipline. Although relatively minor, they reflected a belief among the rank and file that their sacrifices were not appreciated by their government or senior officers.[201] Combatants on both sides claimed the battle was the most psychologically exhausting of the entire war; recognising this, Philippe Pétain frequently rotated divisions, a process known as the noria system. While this ensured units were withdrawn before their ability to fight was significantly eroded, it meant a high proportion of the French army was affected by the battle.[202] By the beginning of 1917, morale was brittle, even in divisions with good combat records.[203]

In December 1916, Robert Nivelle replaced Pétain as commander of French armies on the Western Front and began planning a spring attack in Champagne, part of a joint Franco-British operation. Nivelle claimed the capture of his main objective, the Chemin des Dames, would achieve a massive breakthrough and cost no more than 15,000 casualties.[204] Poor security meant German intelligence was well informed on tactics and timetables, but despite this, when the attack began on 16 April the French made substantial gains, before being brought to a halt by the newly built and extremely strong defences of the Hindenburg Line. Nivelle persisted with frontal assaults and by 25 April the French had suffered nearly 135,000 casualties, including 30,000 dead, most incurred in the first two days.[205]

Concurrent British attacks at Arras were more successful, although ultimately of little strategic value.[206] Operating as a separate unit for the first time, the Canadian Corps capture of Vimy Ridge during the battle is viewed by many Canadians as a defining moment in creating a sense of national identity.[207][208] Although Nivelle continued the offensive, on 3 May the 21st Division, which had been involved in some of the heaviest fighting at Verdun, refused orders to go into battle, initiating the French Army mutinies; within days, acts of "collective indiscipline" had spread to 54 divisions, while over 20,000 deserted.[209] Unrest was almost entirely confined to the infantry, whose demands were largely non-political, including better economic support for families at home, and regular periods of leave, which Nivelle had ended.[210]

Files of soldiers with rifles slung follow close behind a tank, there is a dead body in the foreground
Canadian Corps troops at the Battle of Vimy Ridge, 1917
Although the vast majority remained willing to defend their own lines, they refused to participate in offensive action, reflecting a complete breakdown of trust in the army leadership.[211] Nivelle was removed from command on 15 May and replaced by Pétain, who resisted demands for drastic punishment and set about restoring morale by improving conditions. While exact figures are still debated, only 27 men were actually executed, with another 3,000 sentenced to periods of imprisonment; however, the psychological effects were long-lasting, one veteran commenting "Pétain has purified the unhealthy atmosphere...but they have ruined the heart of the French soldier".[212]

The last large-scale offensive of this period was a British attack (with French support) at Passchendaele (July–November 1917). This offensive opened with great promise for the Allies, before bogging down in the October mud. Casualties, though disputed, were roughly equal, at some 200,000–400,000 per side.

The victory of the Central Powers at the Battle of Caporetto led the Allies to convene the Rapallo conference at which they formed the Supreme War Council to co-ordinate planning. Previously, British and French armies had operated under separate commands.

In December, the Central Powers signed an armistice with Russia, thus freeing large numbers of German troops for use in the west. With German reinforcements and new American troops pouring in, the outcome was to be decided on the Western Front. The Central Powers knew that they could not win a protracted war, but they held high hopes for success based on a final quick offensive. Furthermore, both sides became increasingly fearful of social unrest and revolution in Europe. Thus, both sides urgently sought a decisive victory.[213]

In 1917, Emperor Charles I of Austria secretly attempted separate peace negotiations with Clemenceau, through his wife's brother Sixtus in Belgium as an intermediary, without the knowledge of Germany. Italy opposed the proposals. When the negotiations failed, his attempt was revealed to Germany, resulting in a diplomatic catastrophe.[214][215]

In March and April 1917, at the First and Second Battles of Gaza, German and Ottoman forces stopped the advance of the Egyptian Expeditionary Force, which had begun in August 1916 at the Battle of Romani.[216][217] At the end of October, the Sinai and Palestine campaign resumed, when General Edmund Allenby's XXth Corps, XXI Corps and Desert Mounted Corps won the Battle of Beersheba.[218] Two Ottoman armies were defeated a few weeks later at the Battle of Mughar Ridge and, early in December, Jerusalem was captured following another Ottoman defeat at the Battle of Jerusalem.[219][220][221] About this time, Friedrich Freiherr Kress von Kressenstein was relieved of his duties as the Eighth Army's commander, replaced by Djevad Pasha, and a few months later the commander of the Ottoman Army in Palestine, Erich von Falkenhayn, was replaced by Otto Liman von Sanders.[222][223]

In early 1918, the front line was extended and the Jordan Valley was occupied, following the First Transjordan and the Second Transjordan attacks by British Empire forces in March and April 1918.[224] In March, most of the Egyptian Expeditionary Force's British infantry and Yeomanry cavalry were sent to the Western Front as a consequence of the Spring Offensive. They were replaced by Indian Army units. During several months of reorganisation and training of the summer, a number of attacks were carried out on sections of the Ottoman front line. These pushed the front line north to more advantageous positions for the Entente in preparation for an attack and to acclimatise the newly arrived Indian Army infantry. It was not until the middle of September that the integrated force was ready for large-scale operations.


Ottoman troops in Jerusalem
The reorganised Egyptian Expeditionary Force, with an additional mounted division, broke Ottoman forces at the Battle of Megiddo in September 1918. In two days, the British and Indian infantry, supported by a creeping barrage, broke the Ottoman front line and captured the headquarters of the Eighth Army (Ottoman Empire) at Tulkarm, the continuous trench lines at Tabsor, Arara, and the Seventh Army (Ottoman Empire) headquarters at Nablus. The Desert Mounted Corps rode through the break in the front line created by the infantry. During virtually continuous operations by Australian Light Horse, British mounted Yeomanry, Indian Lancers, and New Zealand Mounted Rifle brigades in the Jezreel Valley, they captured Nazareth, Afulah and Beisan, Jenin, along with Haifa on the Mediterranean coast and Daraa east of the Jordan River on the Hejaz railway. Samakh and Tiberias on the Sea of Galilee were captured on the way northwards to Damascus. Meanwhile, Chaytor's Force of Australian light horse, New Zealand mounted rifles, Indian, British West Indies and Jewish infantry captured the crossings of the Jordan River, Es Salt, Amman and at Ziza most of the Fourth Army (Ottoman Empire). The Armistice of Mudros, signed at the end of October, ended hostilities with the Ottoman Empire when fighting was continuing north of Aleppo.

The Battle of Passchendaele took place on the Western Front, from July to November 1917. The British were fighting for control of the ridges south and east of the Belgian city of Ypres in West Flanders, as part of a strategy decided by the Allies at conferences in November 1916 and May 1917. Passchendaele lies on the last ridge east of Ypres, 5 mi (8.0 km) from Roulers (now Roeselare), a junction of the Bruges-(Brugge)-to-Kortrijk railway. The station at Roulers was on the main supply route of the German 4th Army. Once Passchendaele Ridge had been captured, the Allied advance was to continue to a line from Thourout (now Torhout) to Couckelaere (Koekelare).

Ludendorff drew up plans (codenamed Operation Michael) for the 1918 offensive on the Western Front. The spring offensive sought to divide the British and French forces with a series of feints and advances. The German leadership hoped to end the war before significant US forces arrived. The operation commenced on 21 March 1918 with an attack on British forces near Saint-Quentin. German forces achieved an unprecedented advance of 60 kilometres (37 mi).[226]

British and French trenches were penetrated using novel infiltration tactics, also named Hutier tactics after General Oskar von Hutier, by specially trained units called stormtroopers. Previously, attacks had been characterised by long artillery bombardments and massed assaults. In the spring offensive of 1918, however, Ludendorff used artillery only briefly and infiltrated small groups of infantry at weak points. They attacked command and logistics areas and bypassed points of serious resistance. More heavily armed infantry then destroyed these isolated positions. This German success relied greatly on the element of surprise.[227]


British 55th (West Lancashire) Division soldiers blinded by tear gas during the Battle of Estaires, 10 April 1918
The front moved to within 120 kilometres (75 mi) of Paris. Three heavy Krupp railway guns fired 183 shells on the capital, causing many Parisians to flee. The initial offensive was so successful that Kaiser Wilhelm II declared 24 March a national holiday. Many Germans thought victory was near. After heavy fighting, however, the offensive was halted. Lacking tanks or motorised artillery, the Germans were unable to consolidate their gains. The problems of re-supply were also exacerbated by increasing distances that now stretched over terrain that was shell-torn and often impassable to traffic.[228]

Following Operation Michael, Germany launched Operation Georgette against the northern English Channel ports. The Allies halted the drive after limited territorial gains by Germany. The German Army to the south then conducted Operations Blücher and Yorck, pushing broadly towards Paris. Germany launched Operation Marne (Second Battle of the Marne) on 15 July, in an attempt to encircle Reims. The resulting counter-attack, which started the Hundred Days Offensive, marked the first successful Allied offensive of the war. By 20 July, the Germans had retreated across the Marne to their starting lines,[229] having achieved little, and the German Army never regained the initiative. German casualties between March and April 1918 were 270,000, including many highly trained stormtroopers.

Meanwhile, Germany was falling apart at home. Anti-war marches became frequent and morale in the army fell. Industrial output was half the 1913 levels.

The Allied counteroffensive, known as the Hundred Days Offensive, began on 8 August 1918, with the Battle of Amiens. The battle involved over 400 tanks and 120,000 British, Dominion, and French troops, and by the end of its first day a gap 24 kilometres (15 mi) long had been created in the German lines. The defenders displayed a marked collapse in morale, causing Ludendorff to refer to this day as the "Black Day of the German army".[231][232][233] After an advance as far as 23 kilometres (14 mi), German resistance stiffened, and the battle was concluded on 12 August.

Rather than continuing the Amiens battle past the point of initial success, as had been done so many times in the past, the Allies shifted attention elsewhere. Allied leaders had now realised that to continue an attack after resistance had hardened was a waste of lives, and it was better to turn a line than to try to roll over it. They began to undertake attacks in quick order to take advantage of successful advances on the flanks, then broke them off when each attack lost its initial impetus.[234]

The day after the Offensive began, Ludendorff said: "We cannot win the war any more, but we must not lose it either." On 11 August, he offered his resignation to the Kaiser, who refused it, replying, "I see that we must strike a balance. We have nearly reached the limit of our powers of resistance. The war must be ended."[235] On 13 August, at Spa, Hindenburg, Ludendorff, the Chancellor, and Foreign Minister Hintz agreed that the war could not be ended militarily and, on the following day, the German Crown Council decided that victory in the field was now most improbable. Austria and Hungary warned that they could continue the war only until December, and Ludendorff recommended immediate peace negotiations. Prince Rupprecht warned Prince Maximilian of Baden: "Our military situation has deteriorated so rapidly that I no longer believe we can hold out over the winter; it is even possible that a catastrophe will come earlier."[236]

British and Dominion forces launched the next phase of the campaign with the Battle of Albert on 21 August.[237] The assault was widened by French[236] and then further British forces in the following days. During the last week of August, the Allied pressure along a 110-kilometre (68 mi) front against the enemy was heavy and unrelenting. From German accounts, "Each day was spent in bloody fighting against an ever and again on-storming enemy, and nights passed without sleep in retirements to new lines."[234]

Faced with these advances, on 2 September the German Oberste Heeresleitung ("Supreme Army Command") issued orders to withdraw in the south to the Hindenburg Line. This ceded without a fight the salient seized the previous April.[238] According to Ludendorff, "We had to admit the necessity ... to withdraw the entire front from the Scarpe to the Vesle."[239][page needed] In nearly four weeks of fighting beginning on 8 August, over 100,000 German prisoners were taken. The German High Command realised that the war was lost and made attempts to reach a satisfactory end. On 10 September Hindenburg urged peace moves to Emperor Charles of Austria, and Germany appealed to the Netherlands for mediation. On 14 September Austria sent a note to all belligerents and neutrals suggesting a meeting for peace talks on neutral soil, and on 15 September Germany made a peace offer to Belgium. Both peace offers were rejected.[236]

The Battle of Albert (1–13 July 1916) is the British name for the first two weeks of British–French offensive operations of the Battle of the Somme. The Allied preparatory artillery bombardment commenced on 24 June and the British–French infantry attacked on 1 July, on the south bank from Foucaucourt to the Somme and from the Somme north to Gommecourt, 2 mi (3.2 km) beyond Serre. The French Sixth Army and the right wing of the British Fourth Army inflicted a considerable defeat on the German 2nd Army but from near the Albert–Bapaume road to Gommecourt, the British attack was a disaster, where most of the c. 57,000 British casualties of the day were incurred. Against the wishes of General Joseph Joffre, General Sir Douglas Haig abandoned the offensive north of the road to reinforce the success in the south, where the British–French forces pressed forward through several intermediate lines closer to the German second position.

The French Sixth Army advanced across the Flaucourt plateau south of the Somme and reached Flaucourt village by the evening of 3 July, taking Belloy-en-Santerre and Feullières on 4 July. The French also pierced the German third line opposite Péronne at La Maisonette and Biaches by the evening of 10 July. German reinforcements were then able to slow the French advance and defeat attacks on Barleux. On the north bank, XX Corps was ordered to consolidate the ground captured on 1 July, except for the completion of the advance to the first objective at Hem next to the river, which was captured on 5 July. Some minor attacks took place and German counter-attacks at Hem on 6 to 7 July nearly retook the village. A German attack at Bois Favières delayed a joint British–French attack from Hardecourt to Trônes Wood by 24 hours until 8 July.

British attacks south of the road between Albert and Bapaume began on 2 July, despite congested supply routes to the French XX Corps and the three British corps in the area. La Boisselle near the road was captured on 4 July, Bernafay and Caterpillar woods were occupied from 3 to 4 July and then fighting to capture Trônes Wood, Mametz Wood and Contalmaison took place until early on 14 July, when the Battle of Bazentin Ridge (14–17 July) began. German reinforcements reaching the Somme front were thrown into the defensive battle as soon as they arrived and had many casualties, as did the British attackers. Both sides were reduced to piecemeal operations, which were hurried, poorly organised and sent troops unfamiliar with the ground into action with inadequate reconnaissance. Attacks were poorly supported by artillery-fire, which was not adequately co-ordinated with the infantry and sometimes fired on ground occupied by friendly troops. Much criticism has been made of the British attacks as uncoordinated, tactically crude and wasteful of manpower, which gave the Germans an opportunity to concentrate their inferior resources on narrow fronts.

The loss of about 57,000 British casualties in one day was never repeated but from 2 to 13 July, the British had about 25,000 more casualties; the rate of loss changed from about 60,000 to 2,083 per day. From 1 to 10 July, the Germans had 40,187 casualties against a British total of about 85,000 from 1 to 13 July. The effect of the battle on the defenders has received less attention in English-language writing. The strain imposed by the British attacks after 1 July and the French advance on the south bank led General Fritz von Below to issue an order of the day on 3 July, forbidding voluntary withdrawals ("The enemy should have to carve his way over heaps of corpses.") after Falkenhayn had sacked Generalmajor Paul Grünert [de], the 2nd Army Chief of Staff and General der Infanterie Günther von Pannewitz [de], the commander of XVII Corps, for ordering the corps to withdraw to the third position close to Péronne. The German offensive at Verdun had already been reduced on 24 June to conserve manpower and ammunition; after the failure to capture Fort Souville at Verdun on 12 July, Falkenhayn ordered a "strict defensive" and the transfer of more troops and artillery to the Somme front, which was the first strategic effect of the British–French offensive.

In September the Allies advanced to the Hindenburg Line in the north and centre. The Germans continued to fight strong rear-guard actions and launched numerous counterattacks, but positions and outposts of the Line continued to fall, with the BEF alone taking 30,441 prisoners in the last week of September. On 24 September an assault by both the British and French came within 3 kilometres (2 mi) of St. Quentin. The Germans had now retreated to positions along or behind the Hindenburg Line. That same day, Supreme Army Command informed the leaders in Berlin that armistice talks were inevitable.[236]

The final assault on the Hindenburg Line began with the Meuse-Argonne offensive, launched by American and French troops on 26 September. The following week, co-operating American and French units broke through in Champagne at the Battle of Blanc Mont Ridge, forcing the Germans off the commanding heights, and closing towards the Belgian frontier.[240] On 8 October the line was pierced again by British and Dominion troops at the Battle of Cambrai.[241] The German army had to shorten its front and use the Dutch frontier as an anchor to fight rear-guard actions as it fell back towards Germany.

When Bulgaria signed a separate armistice on 29 September, Ludendorff, having been under great stress for months, suffered something similar to a breakdown. It was evident that Germany could no longer mount a successful defence. The collapse of the Balkans meant that Germany was about to lose its main supplies of oil and food. Its reserves had been used up, even as US troops kept arriving at the rate of 10,000 per day.[242][243][244]

Allied forces started the Vardar offensive on 15 September at two key points: Dobro Pole and near Dojran Lake. In the Battle of Dobro Pole, the Serbian and French armies had success after a three day long battle with relatively small casualties, and subsequently made a breakthrough in the front, something which was rarely seen in World War I. After the front was broken, Allied forces started to liberate Serbia and reached Skopje at 29 September after which Bulgaria signed an armistice with the Allies on 30 September. German Emperor Wilhelm II wrote a telegram to Bulgarian Tsar Ferdinand I: "Disgraceful! 62,000 Serbs decided the war!".[245][246]

Allied armies continued the liberation of Serbia while Germany unsuccessfully tried to establish new front lines near Niš by sending troops from Romania. After the Serbian army entered Niš on 11 October, Germany left Austro-Hungary to organize the Balkan front. On 1 November Serbian forces liberated Belgrade and started to cross over the border with Austria-Hungary. Austria-Hungary was politically disintegrating and signed an armistice with Italy on 3 November, leaving Germany alone in Europe. On 6 November the Serbian Army liberated Sarajevo and Novi Sad on 9 November. The non-German peoples of Austria-Hungary started to organize independent states in the territory of Austria-Hungary, which it was unable to prevent.

News of Germany's impending military defeat spread throughout the German armed forces. The threat of mutiny was rife. Admiral Reinhard Scheer and Ludendorff decided to launch a last attempt to restore the "valour" of the German Navy.

In northern Germany, the German Revolution of 1918–1919 began at the end of October 1918. Units of the German Navy refused to set sail for a last, large-scale operation in a war they believed to be as good as lost, initiating the uprising. The sailors' revolt, which then ensued in the naval ports of Wilhelmshaven and Kiel, spread across the whole country within days and led to the proclamation of a republic on 9 November 1918, shortly thereafter to the abdication of Kaiser Wilhelm II, and to German surrender.[247][248][249][244]

With the military faltering and with widespread loss of confidence in the Kaiser leading to his abdication and fleeing of the country, Germany moved towards surrender. Prince Maximilian of Baden took charge of a new government on 3 October as Chancellor of Germany to negotiate with the Allies. Negotiations with President Wilson began immediately, in the hope that he would offer better terms than the British and French. Wilson demanded a constitutional monarchy and parliamentary control over the German military.[250] There was no resistance when the Social Democrat Philipp Scheidemann on 9 November declared Germany to be a republic. The Kaiser, kings and other hereditary rulers all were removed from power and Wilhelm fled to exile in the Netherlands. It was the end of Imperial Germany; a new Germany had been born as the Weimar Republic.[251]

The collapse of the Central Powers came swiftly. Bulgaria was the first to sign an armistice, the Armistice of Salonica on 29 September 1918.[252] German Emperor Wilhelm II in his telegram to Bulgarian Tsar Ferdinand I described situation: "Disgraceful! 62,000 Serbs decided the war!".[253][254] On the same day, the German Supreme Army Command informed Kaiser Wilhelm II and the Imperial Chancellor Count Georg von Hertling, that the military situation facing Germany was hopeless.[255]

On 24 October, the Italians began a push that rapidly recovered territory lost after the Battle of Caporetto. This culminated in the Battle of Vittorio Veneto, which marked the end of the Austro-Hungarian Army as an effective fighting force. The offensive also triggered the disintegration of the Austro-Hungarian Empire. During the last week of October, declarations of independence were made in Budapest, Prague, and Zagreb. On 29 October, the imperial authorities asked Italy for an armistice, but the Italians continued advancing, reaching Trento, Udine, and Trieste. On 3 November, Austria-Hungary sent a flag of truce to ask for an armistice (Armistice of Villa Giusti). The terms, arranged by telegraph with the Allied Authorities in Paris, were communicated to the Austrian commander and accepted. The Armistice with Austria was signed in the Villa Giusti, near Padua, on 3 November. Austria and Hungary signed separate armistices following the overthrow of the Habsburg monarchy. In the following days, the Italian Army occupied Innsbruck and all Tyrol with over 20,000 soldiers.[256]

On 30 October, the Ottoman Empire capitulated, signing the Armistice of Mudros.[252]


Ferdinand Foch, second from right, pictured outside the carriage in Compiègne after agreeing to the armistice that ended the war there. The carriage was later chosen by Nazi Germany as the symbolic setting of Pétain's June 1940 armistice.[257]
On 11 November, at 5:00 am, an armistice with Germany was signed in a railroad carriage at Compiègne. At 11 am on 11 November 1918—"the eleventh hour of the eleventh day of the eleventh month"—a ceasefire came into effect. During the six hours between the signing of the armistice and its taking effect, opposing armies on the Western Front began to withdraw from their positions, but fighting continued along many areas of the front, as commanders wanted to capture territory before the war ended. The occupation of the Rhineland took place following the Armistice. The occupying armies consisted of American, Belgian, British and French forces.

In November 1918, the Allies had ample supplies of manpower and materiel to invade Germany. Yet at the time of the armistice, no Allied force had crossed the German frontier, the Western Front was still some 720 kilometres (450 mi) from Berlin, and the Kaiser's armies had retreated from the battlefield in good order. These factors enabled Hindenburg and other senior German leaders to spread the story that their armies had not really been defeated. This resulted in the stab-in-the-back myth,[258][259] which attributed Germany's defeat not to its inability to continue fighting (even though up to a million soldiers were suffering from the 1918 flu pandemic and unfit to fight), but to the public's failure to respond to its "patriotic calling" and the supposed sabotage of the war effort, particularly by Jews, Socialists, and Bolsheviks.

The Allies had much more potential wealth they could spend on the war. One estimate (using 1913 US dollars) is that the Allies spent $58 billion on the war and the Central Powers only $25 billion. Among the Allies, the UK spent $21 billion and the US $17 billion; among the Central Powers Germany spent $20 billion.[260]

The Franco-Prussian War or Franco-German War, often referred to in France as the War of 1870, was a conflict between the Second French Empire and the North German Confederation led by the Kingdom of Prussia. Lasting from 19 July 1870 to 28 January 1871, the conflict was caused primarily by France's determination to reassert its dominant position in continental Europe, which appeared in question following the decisive Prussian victory over Austria in 1866.[13] According to some historians, Prussian chancellor Otto von Bismarck deliberately provoked the French into declaring war on Prussia in order to induce four independent southern German states—Baden, Württemberg, Bavaria and Hesse-Darmstadt—to join the North German Confederation. Other historians contend that Bismarck exploited the circumstances as they unfolded. All agree that Bismarck recognized the potential for new German alliances, given the situation as a whole.[14]

France mobilised its army on 15 July 1870, leading the North German Confederation to respond with its own mobilisation later that day. On 16 July 1870, the French parliament voted to declare war on Prussia; France invaded German territory on 2 August. The German coalition mobilised its troops much more effectively than the French and invaded northeastern France on 4 August. German forces were superior in numbers, training, and leadership and made more effective use of modern technology, particularly railways and artillery.

A series of hard-fought Prussian and German victories in eastern France, culminating in the Siege of Metz and the Battle of Sedan, resulted in the capture of the French Emperor Napoleon III and the decisive defeat of the army of the Second Empire; a Government of National Defense was formed in Paris on 4 September and continued the war for another five months. German forces fought and defeated new French armies in northern France, then besieged Paris for over four months before it fell on 28 January 1871, effectively ending the war.

In the final days of the war, with German victory all but assured, the German states proclaimed their union as the German Empire under the Prussian king Wilhelm I and Chancellor Bismarck. With the notable exceptions of Austria and German Switzerland, the vast majority of German-speakers were united under a nation-state for the first time. Following an armistice with France, the Treaty of Frankfurt was signed on 10 May 1871, giving Germany billions of francs in war indemnity, as well as most of Alsace and parts of Lorraine, which became the Imperial Territory of Alsace-Lorraine (Reichsland Elsaß-Lothringen).

The war had a lasting impact on Europe. By hastening German unification, the war significantly altered the balance of power on the continent, with the new German state supplanting France as the dominant European land power. Bismarck maintained great authority in international affairs for two decades, developing a reputation for Realpolitik that raised Germany's global stature and influence. In France, it brought a final end to imperial rule and began the first lasting republican government. Resentment over the French government's handling of the war and its aftermath triggered the Paris Commune, a revolutionary uprising which seized and held power for two months before its suppression; the event would influence the politics and policies of the Third Republic.

The causes of the Franco-Prussian War are rooted in the events surrounding the lead up to the unification of the German states under Otto von Bismarck. France had gained the status of being the dominant power of continental Europe as a result of the Franco-Austrian War of 1859. During the Austro-Prussian War of 1866, the Empress Eugénie, Foreign Minister Drouyn de Lhuys and War Minister Jacques Louis Randon were concerned that the power of Prussia might overtake that of France. They unsuccessfully urged Napoleon to mass troops at France's eastern borders while the bulk of the Prussian armies were still engaged in Bohemia as a warning that no territorial changes could be effected in Germany without consulting France.[15]

As a result of Prussia's annexation of several German states which had sided with Austria during the war and the formation of the North German Confederation under Prussia's aegis, French public opinion stiffened and now demanded more firmness as well as territorial compensations. As a result, Napoleon demanded from Prussia a return to the French borders of 1814, with the annexation of Luxembourg, most of Saarland, and the Bavarian Palatinate. Bismarck flatly refused what he disdainfully termed France's politique des pourboires ("tipping policy").[16][17] He then communicated Napoleon III's written territorial demands to Bavaria and the other southern German states of Württemberg, Baden and Hesse-Darmstadt, which hastened the conclusion of defensive military alliances with these states.[18] France had been strongly opposed to any further alliance of German states, which would have threatened French continental dominance.[19]

The only result of French policy was the consent of Prussia to nominal independence for Saxony, Bavaria, Wurttemberg, Baden, and Hessia-Darmstadt; this was a small victory, and one without appeal to a French public which wanted territory and a French army which wanted revenge.[20] The situation did not suit either France, which unexpectedly found itself next to the militarily powerful Prussian-led North German Confederation, or Prussia, whose foremost objective was to complete the process of uniting the German states under its control. Thus, war between the two powers since 1866 was only a matter of time.

In Prussia, some officials considered a war against France both inevitable and necessary to arouse German nationalism in those states that would allow the unification of a great German empire. This aim was epitomized by Prussian Chancellor Otto von Bismarck's later statement: "I did not doubt that a Franco-German war must take place before the construction of a United Germany could be realised."[21] Bismarck also knew that France should be the aggressor in the conflict to bring the four southern German states to side with Prussia, hence giving Germans numerical superiority.[22] He was convinced that France would not find any allies in her war against Germany for the simple reason that "France, the victor, would be a danger to everybody—Prussia to nobody," and he added, "That is our strong point."[23] Many Germans also viewed the French as the traditional destabilizer of Europe, and sought to weaken France to prevent further breaches of the peace.[24]

The immediate cause of the war was the candidacy of Leopold of Hohenzollern-Sigmaringen to the throne of Spain. France feared an encirclement resulting from an alliance between Prussia and Spain. The Hohenzollern prince's candidacy was withdrawn under French diplomatic pressure, but Otto von Bismarck goaded the French into declaring war by releasing an altered summary of the Ems Dispatch, a telegram sent by William I rejecting French demands that Prussia never again support a Hohenzollern candidacy. Bismarck's summary, as mistranslated by the French press Havas, made it sound as if the king had treated the French envoy in a demeaning fashion, which inflamed public opinion in France.[22]

French historians François Roth and Pierre Milza argue that Napoleon III was pressured by a bellicose press and public opinion and thus sought war in response to France's diplomatic failures to obtain any territorial gains following the Austro-Prussian War.[25] Napoleon III believed he would win a conflict with Prussia. Many in his court, such as Empress Eugénie, also wanted a victorious war to resolve growing domestic political problems, restore France as the undisputed leading power in Europe, and ensure the long-term survival of the House of Bonaparte. A national plebiscite held on 8 May 1870, which returned results overwhelmingly in favor of the Emperor's domestic agenda gave the impression that the regime was politically popular and in a position to confront Prussia. Within days of the plebiscite, France's pacifist Foreign Minister Napoléon, comte Daru, was replaced by Agenor, duc de Gramont, a fierce opponent of Prussia who, as French Ambassador to Austria in 1866, had advocated an Austro-French military alliance against Prussia. Napoleon III's worsening health problems made him less and less capable of reining in Empress Eugénie, Gramont and the other members of the war party, known collectively as the "mameluks". For Bismarck, the nomination of Gramont was seen as "a highly bellicose symptom".[26]

The Ems telegram of 13 July 1870 had exactly the effect on French public opinion that Bismarck had intended. "This text produced the effect of a red flag on the Gallic bull”,[27] Bismarck later wrote. Gramont, the French foreign minister, declared that he felt "he had just received a slap". The leader of the monarchists in Parliament, Adolphe Thiers, spoke for moderation, arguing that France had won the diplomatic battle and there was no reason for war, but he was drowned out by cries that he was a traitor and a Prussian. Napoleon's new prime minister, Emile Ollivier, declared that France had done all that it could humanly and honorably do to prevent the war, and that he accepted the responsibility "with a light heart". A crowd of 15,000–20,000 people, carrying flags and patriotic banners, marched through the streets of Paris, demanding war. French mobilization was ordered early on 15 July.[28] Upon receiving news of the French mobilization, the North German Confederation mobilized on the night of 15–16 July, while Bavaria and Baden did likewise on 16 July and Württemberg on 17 July.[29] On 19 July 1870, the French sent a declaration of war to the Prussian government.[30] The southern German states immediately sided with Prussia.[22]

Napoleonic France had no documented alliance with other powers and entered the war virtually without allies. The calculation was for a victorious offensive, which, as the French Foreign Minister Gramont stated, was "the only way for France to lure the wary Austrians, Italians and Danes into the French alliance".[31] The involvement of Russia on the side of France was not considered by her at all, since Russia made the lifting of restrictions on its naval construction on the Black Sea imposed on Russia by the Treaty of Paris following the Crimean War a precondition for the union. But Imperial France was not ready to do this. "Bonaparte did not dare to encroach on the Paris Treaty: the worse things turned out in the present, the more precious the heritage of the past became".[32]

For the organization of the two armies at the beginning of the war, see Franco-Prussian War order of battle.

The French Army consisted in peacetime of approximately 426,000 soldiers, some of them regulars, others conscripts who until March 1869 were selected by ballot and served for the comparatively long period of seven years. Some of them were veterans of previous French campaigns in the Crimean War, Algeria, the Franco-Austrian War in Italy, and in the Mexican campaign. However, following the "Seven Weeks War" between Prussia and Austria four years earlier, it had been calculated that, with commitments in Algeria and elsewhere, the French Army could field only 288,000 men to face the Prussian Army, when potentially 1,000,000 would be required.[33] Under Marshal Adolphe Niel, urgent reforms were made. Universal conscription and a shorter period of service gave increased numbers of reservists, who would swell the army to a planned strength of 800,000 on mobilisation. Those who for any reason were not conscripted were to be enrolled in the Garde Mobile, a militia with a nominal strength of 400,000. However, the Franco-Prussian War broke out before these reforms could be completely implemented. The mobilisation of reservists was chaotic and resulted in large numbers of stragglers, while the Garde Mobile were generally untrained and often mutinous.[34]

French infantry were equipped with the breech-loading Chassepot rifle, one of the most modern mass-produced firearms in the world at the time, with 1,037,555 available in French inventories. With a rubber ring seal and a smaller bullet, the Chassepot had a maximum effective range of some 1,500 metres (4,900 ft) with a short reloading time.[35] French tactics emphasised the defensive use of the Chassepot rifle in trench-warfare style fighting—the so-called feu de bataillon.[36] The artillery was equipped with rifled, muzzle-loaded La Hitte guns.[37] The army also possessed a precursor to the machine-gun: the mitrailleuse, which could unleash significant, concentrated firepower but nevertheless lacked range and was comparatively immobile, and thus prone to being easily overrun. The mitrailleuse was mounted on an artillery gun carriage and grouped in batteries in a similar fashion to cannon.[35]

The army was nominally led by Napoleon III, with Marshals François Achille Bazaine and Patrice de MacMahon in command of the field armies.[38] However, there was no previously arranged plan of campaign in place. The only campaign plan prepared between 1866 and 1870 was a defensive one.[19]

The German army comprised that of the North German Confederation led by the Kingdom of Prussia, and the South German states drawn in under the secret clause of the preliminary peace of Nikolsburg, 26 July 1866,[39] and formalised in the Treaty of Prague, 23 August 1866.[40]

Recruitment and organisation of the various armies were almost identical, and based on the concept of conscripting annual classes of men who then served in the regular regiments for a fixed term before being moved to the reserves. This process gave a theoretical peace time strength of 382,000 and a wartime strength of about 1,189,000.[41]

German tactics emphasised encirclement battles like Cannae and using artillery offensively whenever possible. Rather than advancing in a column or line formation, Prussian infantry moved in small groups that were harder to target by artillery or French defensive fire.[42] The sheer number of soldiers available made encirclement en masse and destruction of French formations relatively easy.[43]

The army was equipped with the Dreyse needle gun renowned for its use at the Battle of Königgrätz, which was by this time showing the age of its 25-year-old design.[35] The rifle had a range of only 600 m (2,000 ft) and lacked the rubber breech seal that permitted aimed shots.[44] The deficiencies of the needle gun were more than compensated for by the famous Krupp 6-pounder (6 kg despite the gun being called a 6-pounder, the rifling technology enabled guns to fire twice the weight of projectiles in the same calibre) steel breech-loading cannons being issued to Prussian artillery batteries.[45] Firing a contact-detonated shell, the Krupp gun had a longer range and a higher rate of fire than the French bronze muzzle loading cannon, which relied on time fuses.[46]

The Prussian army was controlled by the General Staff, under General Helmuth von Moltke. The Prussian army was unique in Europe for having the only such organisation in existence, whose purpose in peacetime was to prepare the overall war strategy, and in wartime to direct operational movement and organise logistics and communications.[47] The officers of the General Staff were hand-picked from the Prussian Kriegsakademie (War Academy). Moltke embraced new technology, particularly the railroad and telegraph, to coordinate and accelerate mobilisation of large forces.[48]

On 28 July 1870 Napoleon III left Paris for Metz and assumed command of the newly titled Army of the Rhine, some 202,448 strong and expected to grow as the French mobilization progressed.[49] Marshal MacMahon took command of I Corps (4 infantry divisions) near Wissembourg; Marshal François Canrobert brought VI Corps (4 infantry divisions) to Châlons-sur-Marne in northern France as a reserve and to guard against a Prussian advance through Belgium.[50]

A pre-war plan laid down by the late Marshal Niel called for a strong French offensive from Thionville towards Trier and into the Prussian Rhineland. This plan was discarded in favour of a defensive plan by Generals Charles Frossard and Bartélemy Lebrun, which called for the Army of the Rhine to remain in a defensive posture near the German border and repel any Prussian offensive. As Austria, along with Bavaria, Württemberg, and Baden were expected to join in a revenge war against Prussia, I Corps would invade the Bavarian Palatinate and proceed to "free" the four South German states in concert with Austro-Hungarian forces. VI Corps would reinforce either army as needed.[51]

Unfortunately for Frossard's plan, the Prussian army mobilised far more rapidly than expected. The Austro-Hungarians, still reeling after their defeat by Prussia in the Austro-Prussian War, were treading carefully before stating that they would only side with France if the south Germans viewed the French positively. This did not materialize as the four South German states had come to Prussia's aid and were mobilizing their armies against France.[52]

Napoleon III was under substantial domestic pressure to launch an offensive before the full might of Moltke's forces was mobilized and deployed. Reconnaissance by Frossard's forces had identified only the Prussian 16th Infantry Division guarding the border town of Saarbrücken, right before the entire Army of the Rhine. Accordingly, on 31 July the Army marched forward toward the Saar River to seize Saarbrücken.[53]

General Frossard's II Corps and Marshal Bazaine's III Corps crossed the German border on 2 August, and began to force the Prussian 40th Regiment of the 16th Infantry Division from the town of Saarbrücken with a series of direct attacks. The Chassepot rifle proved its worth against the Dreyse rifle, with French riflemen regularly outdistancing their Prussian counterparts in the skirmishing around Saarbrücken. However the Prussians resisted strongly, and the French suffered 86 casualties to the Prussian 83 casualties. Saarbrücken also proved to be a major obstacle in terms of logistics. Only one railway there led to the German hinterland but could be easily defended by a single force, and the only river systems in the region ran along the border instead of inland.[54] While the French hailed the invasion as the first step towards the Rhineland and later Berlin, General Edmond Le Bœuf and Napoleon III were receiving alarming reports from foreign news sources of Prussian and Bavarian armies massing to the southeast in addition to the forces to the north and northeast.[55]

Moltke had indeed massed three armies in the area—the Prussian First Army with 50,000 men, commanded by General Karl von Steinmetz opposite Saarlouis, the Prussian Second Army with 134,000 men commanded by Prince Friedrich Karl opposite the line Forbach-Spicheren, and the Prussian Third Army with 120,000 men commanded by Crown Prince Friedrich Wilhelm, poised to cross the border at Wissembourg.[56]

Upon learning from captured Prussian soldiers and a local area police chief that the Prussian Crown Prince's Third Army was just 30 miles (48 km) north from Saarbrücken near the Rhine river town Wissembourg, General Le Bœuf and Napoleon III decided to retreat to defensive positions. General Frossard, without instructions, hastily withdrew his elements of the Army of the Rhine in Saarbrücken back across the river to Spicheren and Forbach.[57]

Marshal MacMahon, now closest to Wissembourg, spread his four divisions 20 miles (32 km) to react to any Prussian-Bavarian invasion. This organization was due to a lack of supplies, forcing each division to seek out food and forage from the countryside and from the representatives of the army supply arm that was supposed to furnish them with provisions. What made a bad situation much worse was the conduct of General Auguste-Alexandre Ducrot, commander of the 1st Division. He told General Abel Douay, commander of the 2nd Division, on 1 August that "The information I have received makes me suppose that the enemy has no considerable forces very near his advance posts, and has no desire to take the offensive".[58] Two days later, he told MacMahon that he had not found "a single enemy post ... it looks to me as if the menace of the Bavarians is simply bluff". Even though Ducrot shrugged off the possibility of an attack by the Germans, MacMahon tried to warn his other three division commanders, without success.[59]

The first action of the Franco-Prussian War took place on 4 August 1870. This battle saw the unsupported division of General Douay of I Corps, with some attached cavalry, which was posted to watch the border, attacked in overwhelming but uncoordinated fashion by the German 3rd Army. During the day, elements of a Bavarian and two Prussian corps became engaged and were aided by Prussian artillery, which blasted holes in the city defenses. Douay held a very strong position initially, thanks to the accurate long-range rapid fire of the Chassepot rifles, but his force was too thinly stretched to hold it. Douay was killed in the late morning when a caisson of the divisional mitrailleuse battery exploded near him; the encirclement of the town by the Prussians then threatened the French avenue of retreat.[60]

The fighting within the town had become extremely intense, becoming a door to door battle of survival. Despite an unceasing attack from Prussian infantry, the soldiers of the 2nd Division kept to their positions. The people of the town of Wissembourg finally surrendered to the Germans. The French troops who did not surrender retreated westward, leaving behind 1,000 dead and wounded and another 1,000 prisoners and all of their remaining ammunition.[61] The final attack by the Prussian troops also cost c. 1,000 casualties. The German cavalry then failed to pursue the French and lost touch with them. The attackers had an initial superiority of numbers, a broad deployment which made envelopment highly likely but the effectiveness of French Chassepot-rifle fire inflicted costly repulses on infantry attacks, until the French infantry had been extensively bombarded by the Prussian artillery.[62]

The Battle of Spicheren on 5 August was the second of three critical French defeats. Moltke had originally planned to keep Bazaine's army on the Saar River until he could attack it with the 2nd Army in front and the 1st Army on its left flank, while the 3rd Army closed towards the rear. The aging General von Steinmetz made an overzealous, unplanned move, leading the 1st Army south from his position on the Moselle. He moved straight toward the town of Spicheren, cutting off Prince Frederick Charles from his forward cavalry units in the process.[60]

On the French side, planning after the disaster at Wissembourg had become essential. General Le Bœuf, flushed with anger, was intent upon going on the offensive over the Saar and countering their loss. However, planning for the next encounter was more based upon the reality of unfolding events rather than emotion or pride, as Intendant General Wolff told him and his staff that supply beyond the Saar would be impossible. Therefore, the armies of France would take up a defensive position that would protect against every possible attack point, but also left the armies unable to support each other.[61]

While the French army under General MacMahon engaged the German 3rd Army at the Battle of Wörth, the German 1st Army under Steinmetz finished their advance west from Saarbrücken. A patrol from the German 2nd Army under Prince Friedrich Karl of Prussia spotted decoy fires nearby and Frossard's army farther off on a distant plateau south of the town of Spicheren, and took this as a sign of Frossard's retreat. Ignoring Moltke's plan again, both German armies attacked Frossard's French 2nd Corps, fortified between Spicheren and Forbach.[62]

The French were unaware of German numerical superiority at the beginning of the battle as the German 2nd Army did not attack all at once. Treating the oncoming attacks as merely skirmishes, Frossard did not request additional support from other units. By the time he realized what kind of a force he was opposing, it was too late. Seriously flawed communications between Frossard and those in reserve under Bazaine slowed down so much that by the time the reserves received orders to move out to Spicheren, German soldiers from the 1st and 2nd armies had charged up the heights.[63] Because the reserves had not arrived, Frossard erroneously believed that he was in grave danger of being outflanked, as German soldiers under General von Glume were spotted in Forbach. Instead of continuing to defend the heights, by the close of battle after dusk he retreated to the south. The German casualties were relatively high due to the advance and the effectiveness of the Chassepot rifle. They were quite startled in the morning when they had found out that their efforts were not in vain—Frossard had abandoned his position on the heights.[64]

The Battle of Wörth began when the two armies clashed again on 6 August near Wörth in the town of Frœschwiller, about 10 miles (16 km) from Wissembourg. The Crown Prince of Prussia's 3rd army had, on the quick reaction of his Chief of Staff General von Blumenthal, drawn reinforcements which brought its strength up to 140,000 troops. The French had been slowly reinforced and their force numbered only 35,000. Although badly outnumbered, the French defended their position just outside Frœschwiller. By afternoon, the Germans had suffered c. 10,500 killed or wounded and the French had lost a similar number of casualties and another c. 9,200 men taken prisoner, a loss of about 50%. The Germans captured Fröschwiller which sat on a hilltop in the centre of the French line. Having lost any hope for victory and facing a massacre, the French army disengaged and retreated in a westerly direction towards Bitche and Saverne, hoping to join French forces on the other side of the Vosges mountains. The German 3rd army did not pursue the French but remained in Alsace and moved slowly south, attacking and destroying the French garrisons in the vicinity.[65]

About 160,000 French soldiers were besieged in the fortress of Metz following the defeats on the frontier. A retirement from Metz to link up with French forces at Châlons was ordered on 15 August and spotted by a Prussian cavalry patrol under Major Oskar von Blumenthal. Next day a grossly outnumbered Prussian force of 30,000 men of III Corps (of the 2nd Army) under General Constantin von Alvensleben, found the French Army near Vionville, east of Mars-la-Tour.[66]

Despite odds of four to one, the III Corps launched a risky attack. The French were routed and the III Corps captured Vionville, blocking any further escape attempts to the west. Once blocked from retreat, the French in the fortress of Metz had no choice but to engage in a fight that would see the last major cavalry engagement in Western Europe. The battle soon erupted, and III Corps was shattered by incessant cavalry charges, losing over half its soldiers. The German Official History recorded 15,780 casualties and French casualties of 13,761 men.[67]

On 16 August, the French had a chance to sweep away the key Prussian defense, and to escape. Two Prussian corps had attacked the French advance guard, thinking that it was the rearguard of the retreat of the French Army of the Meuse. Despite this misjudgment the two Prussian corps held the entire French army for the whole day. Outnumbered 5 to 1, the extraordinary élan of the Prussians prevailed over gross indecision by the French. The French had lost the opportunity to win a decisive victory.[68]

The Battle of Gravelotte, or Gravelotte–St. Privat (18 August), was the largest battle in the Franco-Prussian War. It was fought about 6 miles (9.7 km) west of Metz, where on the previous day, having intercepted the French army's retreat to the west at the Battle of Mars-La-Tour, the Prussians were now closing in to complete the destruction of the French forces. The combined German forces, under Field Marshal Count Helmuth von Moltke, were the Prussian First and Second Armies of the North German Confederation numbering about 210 infantry battalions, 133 cavalry squadrons, and 732 artillery pieces totaling 188,332 officers and men. The French Army of the Rhine, commanded by Marshal François-Achille Bazaine, numbering about 183 infantry battalions, 104 cavalry squadrons, backed by 520 artillery pieces, totaling 112,800 officers and men, dug in along high ground with their southern left flank at the town of Rozérieulles, and their northern right flank at St. Privat.

On 18 August, the battle began when at 08:00 Moltke ordered the First and Second Armies to advance against the French positions. The French were dug in with trenches and rifle pits with their artillery and their mitrailleuses in concealed positions. Backed by artillery fire, Steinmetz's VII and VIII Corps launched attacks across the Mance ravine, all of which were defeated by French rifle and mitrailleuse firepower, forcing the two German corps' to withdraw to Rezonville. The Prussian 1st Guards Infantry Division assaulted French-held St. Privat and was pinned down by French fire from rifle pits and trenches. The Second Army under Prince Frederick Charles used its artillery to pulverize the French position at St. Privat. His XII Corps took the town of Roncourt and helped the Guard conquer St. Privat, while Eduard von Fransecky's II Corps advanced across the Mance ravine. The fighting died down at 22:00.

The next morning the French Army of the Rhine retreated to Metz where they were besieged and forced to surrender two months later. A grand total of 20,163 German troops were killed, wounded or missing in action during the August 18 battle. The French losses were 7,855 killed and wounded along with 4,420 prisoners of war (half of them were wounded) for a total of 12,275.

With the defeat of Marshal Bazaine's Army of the Rhine at Gravelotte, the French retreated to Metz, where they were besieged by over 150,000 Prussian troops of the First and Second Armies. Further military operations on the part of the army under Bazaine's command have drawn numerous criticisms from historians against its commander. It was later stated with derogatory irony that his occupation at that time was writing orders on hygiene and discipline, as well as playing dominoes.[69] Bazaine's surprising inactivity was a great relief to Moltke, who now had time to improve his lines around Metz and intensify the hunt for MacMahon.[70]

At this time, Napoleon III and MacMahon formed the new French Army of Châlons to march on to Metz to rescue Bazaine. Napoleon III personally led the army with Marshal MacMahon in attendance. The Army of Châlons marched northeast towards the Belgian border to avoid the Prussians before striking south to link up with Bazaine. The Prussians took advantage of this maneuver to catch the French in a pincer grip. Moltke left the Prussian First and Second Armies besieging Metz, except three corps detached to form the Army of the Meuse under the Crown Prince of Saxony. With this army and the Prussian Third Army, Moltke marched northward and caught up with the French at Beaumont on 30 August. After a sharp fight in which they lost 5,000 men and 40 cannons, the French withdrew toward Sedan. Having reformed in the town, the Army of Châlons was immediately isolated by the converging Prussian armies. Napoleon III ordered the army to break out of the encirclement immediately. With MacMahon wounded on the previous day, General Auguste Ducrot took command of the French troops in the field.

On 1 September 1870, the battle opened with the Army of Châlons, with 202 infantry battalions, 80 cavalry squadrons and 564 guns, attacking the surrounding Prussian Third and Meuse Armies totaling 222 infantry battalions, 186 cavalry squadrons and 774 guns. General Emmanuel Félix de Wimpffen, the commander of the French V Corps in reserve, hoped to launch a combined infantry and cavalry attack against the Prussian XI Corps. But by 11:00, Prussian artillery took a toll on the French while more Prussian troops arrived on the battlefield. The struggle in the conditions of encirclement turned out to be absolutely impossible for the French—their front was shot through with artillery fire from three sides. The French cavalry, commanded by General Margueritte, launched three desperate attacks on the nearby village of Floing where the Prussian XI Corps was concentrated. Margueritte was mortally wounded leading the very first charge, dying 4 days later, and the two additional charges led to nothing but heavy losses. By the end of the day, with no hope of breaking out, Napoleon III called off the attacks. The French lost over 17,000 men, killed or wounded, with 21,000 captured. The Prussians reported their losses at 2,320 killed, 5,980 wounded and 700 captured or missing. By the next day, on 2 September, Napoleon III surrendered and was taken prisoner with 104,000 of his soldiers. It was an overwhelming victory for the Prussians, who had captured an entire French army and the leader of France. They subsequently paraded the defeated French army in view of the besieged army in Metz, which had an impact on the morale of the defenders. The defeat of the French at Sedan had decided the war in Prussia's favour. One French army was now immobilised and besieged in the city of Metz, and nothing was preventing a Prussian invasion.[71] This defeat was humiliating for the already morally defeated French army and paved the way for the Siege of Paris.

Bazaine, a well-known Bonapartist, at this time allowed himself to be carried away by illusory plans for a political role in France. Unconventional military plans were put forth (by which the Germans would allow the army under Bazaine's command to withdraw from the fortress of Metz to retreat to the south of France, where it would remain until the German armies captured Paris) which were to eliminate the political usurpers and make room for the legitimate imperial authorities with the support of Bazaine's army.[72] Even ignoring moral issues and potential public outcry, this plan seems completely unrealistic. Bismarck and Moltke answered Bazaine's offer of "cooperation" against the "republican menace" with an indifferent shrug.[73] The German press, undoubtedly at the instigation of Bismarck, widely covered this topic, and reported the details of Bazaine's negotiations. The French press could only remain completely silent on this issue. With whom Bazaine negotiated still raises questions among historians. "For a decade, the French were considered him (M. Edmond Regnier) a sinister figure, almost certainly an agent of Bismarck. They would have been more justified in thinking him a buffoon".[74] Undoubtedly, the politically motivated actions of Commander Bazaine led to the passivity of the encircled army at Metz and contributed to the defeat of not only this army, but the country as a whole. Bazaine's army surrendered on 26 October. 173,000 people surrendered, with the Prussians capturing the huge amount of military equipment located in Metz. After the war, Marshal Bazaine was convicted by a French military court.

When news of Napoleon III's surrender at Sedan arrived in Paris, the Second Empire was overthrown by a popular uprising. On 4 September, Jules Favre, Léon Gambetta, and General Louis-Jules Trochu proclaimed a provisional government called the Government of National Defence and a Third Republic.[75] After the German victory at Sedan, most of the French standing army was either besieged in Metz or held prisoner by the Germans, who hoped for an armistice and an end to the war. Bismarck wanted an early peace but had difficulty finding a legitimate French authority with whom to negotiate. The Emperor was a captive and the Empress in exile, but there had been no abdication de jure and the army was still bound by an oath of allegiance to the defunct imperial regime; on the other hand, the Government of National Defence had no electoral mandate.[76]

Prussia's intention was to weaken the political position of France abroad. The defensive position of the new French authorities, who offered Germany an honorable peace and reimbursement of the costs of the war, was presented by Prussia as aggressive; they rejected the conditions put forward and demanded the annexation of the French provinces of Alsace and part of Lorraine. Bismarck was dangling the Emperor over the republic's head, calling Napoleon III "the legitimate ruler of France" and dismissing Gambetta's new republic as no more than "un coup de parti" ("a partisan coup").[71] This policy was to some extent successful; the European press discussed the legitimacy of the French authorities, and Prussia's aggressive position was to some extent understood. Only the United States and Spain recognized the Government of National Defence immediately after the announcement; other countries refused to do this for some time.[77]

The question of legitimacy is rather strange for France after the coup d'état of 1851, since Louis-Napoleon himself only overthrew the Second Republic and rose to the imperial throne by means of a coup d'état.

The Germans expected to negotiate an end to the war, but while the republican government was amenable to war reparations or ceding colonial territories in Africa or Southeast Asia, it would go no further. On behalf of the Government of National Defense, Favre declared on 6 September that France would not "yield an inch of its territory nor a stone of its fortresses".[78] The republic then renewed the declaration of war, called for recruits in all parts of the country, and pledged to drive the German troops out of France by a guerre à outrance ('overwhelming attack').[79] The Germans continued the war, yet could not pin down any proper military opposition in their vicinity. As the bulk of the remaining French armies was digging in near Paris, the German leaders decided to put pressure upon their enemy by attacking there. By 15 September, German troops had reached the outskirts and Moltke issued the orders to surround the city. On 19 September, the Germans surrounded it and erected a blockade, as already established at Metz, completing the encirclement on 20 September.[timeframe?] Bismarck met Favre on 18 September at the Château de Ferrières and demanded a frontier immune to a French war of revenge, which included Strasbourg, Alsace, and most of the Moselle department in Lorraine, of which Metz was the capital. In return for an armistice for the French to elect a National Assembly, Bismarck demanded the surrender of Strasbourg and the fortress city of Toul. To allow supplies into Paris, one of the perimeter forts had to be handed over. Favre was unaware that Bismarck's real aim in making such extortionate demands was to establish a durable peace on Germany's new western frontier, preferably by a peace with a friendly government, on terms acceptable to French public opinion.[clarification needed] An impregnable military frontier was an inferior alternative to him, favoured only by the militant nationalists on the German side.[80]

When the war had begun, European public opinion heavily favoured the Germans; many Italians attempted to sign up as volunteers at the Prussian embassy in Florence and a Prussian diplomat visited Giuseppe Garibaldi in Caprera. Bismarck's demand that France surrender sovereignty over Alsace caused a dramatic shift in that sentiment in Italy, which was best exemplified by the reaction of Garibaldi soon after the revolution in Paris, who told the Movimento of Genoa on 7 September 1870 that "Yesterday I said to you: war to the death to Bonaparte. Today I say to you: rescue the French Republic by every means."[81] Garibaldi went to France and assumed command of the Army of the Vosges, with which he operated around Dijon until the end of the war.

The energetic actions of a part of the government (delegation) in Tours under Gambetta's leadership led to significant success in the formation of a new army. In less than four months, with persistent battles at the front, eleven new corps were formed (Nos. XVI–XXVI). The average success of the formation was equal to six thousand infantrymen and two batteries per day. This success was achieved despite the fact that the military industry and warehouses were concentrated mainly in Paris; all supplies in the province—chiefs, weapons, camps, uniforms, ammunition, equipment, baggage—had to be improvised anew. Many branches of the military industry were re-established in the province. Freedom of communication with foreign markets brought significant benefits; it was possible to make large purchases on foreign markets, mainly English, Belgian, and American. The artillery created by Gambetta in four months—238 batteries—was one and a half times larger than the artillery of imperial France. In the end, eight corps participated in the battles, and three were ready only by the end of January, when a truce was already concluded.[82]

While the Germans had a 2:1 numerical advantage before Napoleon III's surrender, this French recruitment gave them a 2:1 or 3:1 advantage. The French more than tripled their forces during the war, while the Germans did not increase theirs as much; the number of 888,000 mobilized by the North German Union in August increased by only 2% after 3+1⁄2 months, and by the end of the war, six months later, only by 15%, which did not even balance the losses incurred. Prussia was completely unaware of the feverish activity of permanent mobilization. This disparity in forces created a crisis for the Germans at the front in November 1870,[83] which only the release of the large forces besieging the fortress of Metz allowed them to overcome.

Prussian forces commenced the siege of Paris on 19 September 1870. Faced with the blockade, the new French government called for the establishment of several large armies in the French provinces. These new bodies of troops were to march towards Paris and attack the Germans there from various directions at the same time. Armed French civilians were to create a guerilla force—the so-called Francs-tireurs—for the purpose of attacking German supply lines.

Bismarck was an active supporter of the bombardment of the city. He sought to end the war as soon as possible, very much fearing a change in the international situation unfavorable to Prussia, as he himself called it "the intervention of neutrals".[84] Therefore, Bismarck constantly and actively insisted on the early start of the bombardment, despite all the objections of the military command. Von Blumenthal, who commanded the siege, was opposed to the bombardment on moral grounds. In this he was backed by other senior military figures such as the Crown Prince and Moltke. Nevertheless, in January, the Germans fired some 12,000 shells (300–400 daily) into the city.[85]

The siege of the city caused great hardships for the population, especially for the poor from cold and hunger.

Dispatched from Paris as the republican government emissary, Léon Gambetta flew over the German lines in a balloon inflated with coal gas from the city's gasworks and organized the recruitment of the Armée de la Loire. Rumors about an alleged German "extermination" plan infuriated the French and strengthened their support of the new regime. Within a few weeks, five new armies totalling more than 500,000 troops were recruited.[86]

The Germans dispatched some of their troops to the French provinces to detect, attack and disperse the new French armies before they could become a menace. The Germans were not prepared for an occupation of the whole of France.

On 10 October, hostilities began between German and French republican forces near Orléans. At first, the Germans were victorious but the French drew reinforcements and defeated a Bavarian force at the Battle of Coulmiers on 9 November. After the surrender of Metz, more than 100,000 well-trained and experienced German troops joined the German 'Southern Army'. The French were forced to abandon Orléans on 4 December, and were finally defeated at the Battle of Le Mans (10–12 January). A second French army which operated north of Paris was turned back at the Battle of Amiens (27 November), the Battle of Bapaume (3 January 1871) and the Battle of St. Quentin (13 January).[87]

Following the Army of the Loire's defeats, Gambetta turned to General Faidherbe's Army of the North.[88] The army had achieved several small victories at towns such as Ham, La Hallue, and Amiens and was protected by the belt of fortresses in northern France, allowing Faidherbe's men to launch quick attacks against isolated Prussian units, then retreat behind the fortresses. Despite access to the armaments factories of Lille, the Army of the North suffered from severe supply difficulties, which depressed morale. In January 1871, Gambetta forced Faidherbe to march his army beyond the fortresses and engage the Prussians in open battle. The army was severely weakened by low morale, supply problems, the terrible winter weather and low troop quality, whilst general Faidherbe was unable to command due to his poor health, the result of decades of campaigning in West Africa. At the Battle of St. Quentin, the Army of the North suffered a crushing defeat and was scattered, releasing thousands of Prussian soldiers to be relocated to the East.[89]

Following the destruction of the French Army of the Loire, remnants of the Loire army gathered in eastern France to form the Army of the East, commanded by general Charles-Denis Bourbaki. In a final attempt to cut the German supply lines in northeast France, Bourbaki's army marched north to attack the Prussian siege of Belfort and relieve the defenders.

The French troops had a significant advantage (110 thousand soldiers against 40 thousand). The French offensive took the Germans by surprise and by mid-January 1871, the French had reached the Lisaine River, just a few kilometers from the besieged fortress of Belfort.

In the battle of the Lisaine, Bourbaki's men failed to break through German lines commanded by General August von Werder. Bringing in the German 'Southern Army', General von Manteuffel then drove Bourbaki's army into the mountains near the Swiss border. Bourbaki attempted to commit suicide, though survived his wound.[90] Facing annihilation, the last intact French army of 87,000 men (now commanded by General Justin Clinchant)[91] crossed the border and was disarmed and interned by the neutral Swiss near Pontarlier (1 February).

The besieged fortress of Belfort continued to resist until the signing of the armistice, repelling a German attempt to capture the fortress on 27 January, which was some consolation for the French in this stubborn and unhappy campaign.

On 26 January 1871, the Government of National Defence based in Paris negotiated an armistice with the Prussians. With Paris starving, and Gambetta's provincial armies reeling from one disaster after another, French foreign minister Favre went to Versailles on 24 January to discuss peace terms with Bismarck. Bismarck agreed to end the siege and allow food convoys to immediately enter Paris (including trains carrying millions of German army rations), on condition that the Government of National Defence surrender several key fortresses outside Paris to the Prussians. Without the forts, the French Army would no longer be able to defend Paris.

Although public opinion in Paris was strongly against any form of surrender or concession to the Prussians, the Government realised that it could not hold the city for much longer, and that Gambetta's provincial armies would probably never break through to relieve Paris. President Trochu resigned on 25 January and was replaced by Favre, who signed the surrender two days later at Versailles, with the armistice coming into effect at midnight.

On 28 January, a truce was concluded for 21 days, after the exhaustion of food and fuel supplies, the Paris garrison capitulated, the National Guard retained its weapons, while German troops occupied part of the forts of Paris to prevent the possibility of resuming hostilities. But military operations continued in the eastern part of the country, in the area of operation of the Bourbaki army. The French side, having no reliable information about the outcome of the struggle, insisted on excluding this area from the truce in the hope of a successful outcome of the struggle.[93] The Germans did not dissuade the French.

Several sources claim that in his carriage on the way back to Paris, Favre broke into tears, and collapsed into his daughter's arms as the guns around Paris fell silent at midnight. At Bordeaux, Gambetta received word from Paris on 29 January that the Government had surrendered. Furious, he refused to surrender. Jules Simon, a member of the Government arrived from Paris by train on 1 February to negotiate with Gambetta. Another group of three ministers arrived in Bordeaux on 5 February and the following day Gambetta stepped down and surrendered control of the provincial armies to the Government of National Defence, which promptly ordered a cease-fire across France.