I apologise in advance if this guide seems clunky and a little odd, but this is my first written attempt at a guide for a game being published. The basic purpose of this guide is to clarify the 36 Achievements attached to Valkyria Chronicles 4, and the conditions which need to be met in order to gain them.

For the Squad Stories section, I refer you to the excellent community-developed guide authored by Rhomeo "Squad Stories & How They Work", found here: https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1524643576 - This gudie gives you an overview on the conditions for unlocking Squad Stories along with how to unlock some specific characters, and I have found it invaluable. Please note that these will be needed for at least one achievement.

Additionally, another ideal Steam guide that may be helpful is ukie's guide, "All Ace Locations & Corresponding Weapon Drops", found here: https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1528417888 - This should prove helpful in tracking down the enemy Aces and save you some time and Ducats.

As always with such games, Valkyria Chronicles 4 will take some grinding to get all the achievements, but this should explain more clearly how to obtain them all.

Alright... I'll begin by listing these as best I can in the order for which you'll obtain them. Note that there's no actual preset difficulty required for these achievements to be gotten, so gameplay and obtaining may vary depending on your situation. I'll also be listing the medals (officially called Decorations) where appropriate. I'll list all the medals in a separate section, for completion's sake.

The Battle of Siegval (Bronze)
The official description reads: Completed Chapter 4, and won the battle at Siegval. To actually obtain this achievement, you must start Chapter 5. You'll also gain the Siegval Service Medal in-game to commemmorate your victory here.

A March in the Snow (Bronze)
The official description reads: Completed Chapter 7, and rendezvoused with the Centurion. To actually obtain this achievement, you must start Chapter 8. There's no medal to be associated with this achievement in-game.

The Sea Fortress (Bronze)
The official description reads: Completed Chapter 11, and made it past the Sea Fortress. To actually obtain this achievement, you must start Chapter 12. There's no medal to be associated with this achievement.

A Reason to Fight (Bronze)
The official description reads: Completed Chapter 15, and defeated both Walz and Crymaria. To actually obtain this achievement, you must start Chapter 16. There's no medal to be associated with this achievement.

The Final Choice (Bronze)
The official description reads: Completed Chapter 17, and witnessed the end of the war. To actually obtain this achievement, you must start Chapter 18. You may also get the Federation Star of Valor in-game to commemorate your efforts here (confirmation needed - can't remember if this Decoration is awarded here or with the next achievement).

Devotion (Gold)
The official description reads: Completed Chapter 18, and ended Belgar's dark ambitions. To actually obtain this achievement, you have to clear the game. This requires watching the credits and the post-credits cutscene. You may also get the Federation Star of Valor in-game to commemorate your efforts here (confirmation needed - see note for The Final Choice as to why).

Our War's End (Silver)
The official description reads: Kept your promise with Riley Miller. To complete this achievement requires a litte work since it's not automatically given like the first six achievements here. You must first obtain access to the Interlude "A Steamy Ceasefire" and completely view it. Fortunately, there's no combat in this one. This will in turn unlock as a sequence the sub-episodes "Under the Northern Lights" and "The Promised Aurora". Both of these must be viewed. This in turn will unlock "The Final Battle (HARD)", which you must complete to unlock and view the alternative ending, "Our War's End". The achievement is awarded after viewing Our War's End.

Ace Fighter (Bronze)
The official description reads: Defeated an enemy Ace for the first time. This one should be stumbled upon pretty easily, but for those not in the know... Ace enemies are especially powerful variants of their troop types with improved stats and survivability. Picking them off usually requires flanking them and getting a surprise attack in, especially later on in the game. The good news is, you'll loot weapons for the first time you defeat an enemy Ace in each applicable mission. In addition, as a commemorative bonus for getting this achievement, you will get the Honorary Medal of Valor decoration here.

Ace Killer (Silver)
The official description reads: Defeated 15 enemy Aces. Pretty much what it says on the tin here. There's no additional in-game Decoration for earning this achivement.

Agent of Destruction (Silver)
The official description reads: Defeated 1,000 enemy units. Note that Aces may not count towards this achievement, but at the worst they're only a very miniscule portion of your kills anyway. As a commemorative bonus for getting this achievement, you will also get the Gold Medal of Honor decoration here. As markers of your progress, you will also earn the Bronze Medal of Honor at 250 kills, and the Silver Medal of Honor at 500 kills.

Daring Rescuer (Bronze)
The official description reads: Rescued 10 allies in critical condition. This one is what it says on the tin, and should be earned easily enough if you're a conscientious player and rescue your incapacitated and wounded squaddies before the enemy touches them. The order Request Medic and the Ship Order Rescue Squad can be invaluable here if your fallen squaddie is deep in enemy territory and with nobody close by.

Hidden Depths (Bronze)
The official description reads: Completed a squad story for the first time. It's what it says on the tin - you'll claim this one after you clear the full events of the first Squad Story you undertake. No decorations for this one, but at least it's a step towards another achievement later on. Plus, doing Squad Stories is always beneficial - since it changes some negative potentials into positive ones and unlocks new positive potentials. And there's always room for more EXP and Ducats in your coffers!

Squad E, All Present (Silver)
The official description reads: Recruited all squad members. What it says on the tin. To do this, however, you'll have to meet some requirements. Again, Rhomeo's guide in the introduction serves well, but I'll list the spoiler-free requirements here: Complete Hard Skirmishes 1 and 5, save up 1,000,000 Ducats (Note, this is separate from the War Profiteer achievement below, but both can be earned simultaneously if you're gonna be stingy and wanna make life harder for yourself), Complete 3 Squad Stories, Get 5 Decorations, Allow the scout Curtis to go into a critical condition and then rescue him, and one requires you to use the Cenotaph post-game. I won't name names as I am trying to keep this spoiler free. And while it's not required for the achievement, I'd recommend clearing Hard Skirmish 3, then watching the sub-episode "Smells Like Dad".

First of Many (Bronze)
The official description reads: Used the R&D Facility for the first time. What it says on the tin. Incidentally, the title isn't kidding. You will be doing a LOT of R&D if you want to survive later on in this game!

The Hafen Reborn (Bronze)
The official description reads: Developed the Hafen into a heavy tank. To obtain this one requires some work in the R&D Facility, and is something you should obtain easily enough since upgrading you MBT (Main Battle Tank for anyone unfamiliar with the military world's love for TLAs [incidentally, that's Three-Letter Abbreviations] is a well-known must for any Valkyria Chronicles player since this is the most reliable tank killer in most situations). No decoration to go with this one... But you do get to make the Hafen look a lot cooler!

The Federation's Secret Weapon (Silver)
The official description reads: Obtained all ship parts. As part of completing the game, you'll notice that you can only gain four ship parts per Ship Order. To actually get this one, you have to first clear the game, then purchase all the upgrades listed to unlock the Unlock Upgrades: (Insert Name Here) option in the Infirmary. Then purchase the final two upgrades for each Ship Order and the achievement will pop. This will make your Ship Orders a LOT more effective, but they're not the most reliable things in the world, so don't let them be a replacement for good strategic thinking. No decoration for this one.

A Fruitful Chat (Bronze)
The official description reads: Learned an order at the Mess Hall for the first time. Another 'What it says on the tin' achievement. No decoration for this one. This is also helpful in overall battle, and will allow some useful orders to be learned, such as Medic Request, Rapid Deployment, and Resupply.

Military Exemplar (Silver)
The official description reads: Learned all orders. Another 'What it says on the tin' achievement with no decoration. But obtaining this one is simple enough. Learn all orders you can from the Mess Hall and learn all orders gathered by training your squaddies. Training squaddies also leads to some achievements, covered below.

Upward Mobility (Bronze)
The official description reads: One of your squadmates was promoted to Corporal. This basically means your squaddie can now be chosen as a leader and has taken part in at least 40 CP worth of actions. This is also a requirement for unlocking Squad Stories, too, so it's pretty easy to get. Rhomeo's guide explains a lot more here.

Veteran Soldier (Bronze)
The official description reads: One of your classes was promoted to Elite status. Upgrading your classes into Elites is extremely helpful since it unlocks new weapon options and more powerful weapon options at that. For Scouts, it's access to the rifle-underslung grenade launcher. For Shocktroopers, the ever-popular underslung flamethrower. For Lancers, the oft underused and overlooked by some Mortar Lance (admittedly, I don't use these much, but they're good for short-range fire support when you run out of grenades). For Engineers, an upgrade to the Repair Tool, making them more capable with repairing vehicles. For Snipers, the ability to provide intercepting fire (Not as good as it sounds, but at least now they're not TOTALLY defenseless), along with the three-point burst Sniper Rifle (A note here - this is actually useful now, unlike in the first game and the PSP games where it ran out of ammo way too quickly [Note, I cannot speak for the Remastered edition on Steam, but the original version did have this flaw]). For Grenadiers, nothing special. All classes do gain status boosts upon class-up.

Legendary Soldier (Silver)
The official description reads: One of your classes was promoted to Paragon status. This one is only available post-game, since you need to purchase the Upgrade from the infirmary to allow each class to train beyond level 20. But it's helpful, with a greater stat boost than promotion to Elite status. Sadly, no new gadgets.

War Profiteer (Bronze)
The official description reads: Earned 1,000,000 DCT cumulatively. What it says on the tin. Nothing needs to be said here.

Capable Commander (Bronze)
The official description reads: Obtained an A rank on a mission for the first time. What it says on the tin. A note here... Any veteran VC player knows that you get the most EXP and DCT for getting A Ranks, so this is a worthy goal. Depends on the mission and the difficulty, but most missions give you between three to five turns to complete the mission objective to get A rank.

Pride of the Federation (Silver)
The official description reads: Obtained A Ranks on 20 missions. What it says on the tin. Citation needed on this, but I believe you can get the Metirorious Service Medal decoration in-game for obtaining this achievement.

Damage Control (Bronze)
The official description reads: Completed 10 missions without anyone in critical condition. If you play smart early-on, this is easy to obtain. It's unclear if this needs to be in a row or not, but I believe it's just ten missions, not 10 consecurive missions. Citation needed.

Naval Coordination (Bronze)
The official description reads: Gave ship orders 15 times. Most of this will be from using the Rescue Squad or Emergency Repair ship orders, since these are far more valuable than Bombardment or Radar, though Radar has its place in rough conditions to let you know what's ahead. Pretty easy to get. Note that, obviously, you need Ship Orders access to get these.

Follow My Lead (Bronze)
The official description reads: Gave direct commands 15 times. This one is pretty easy to earn, since Direct Command is pretty useful indeed! Coordinated firepower from up to three people, having slower classes piggyback off a faster class's movement to get into position... Ultimately more useful than the APC in some situations. Try and make use of this frequently, and always check your missions to determine what needs doing to achieve it.

That's an Order, Soldier! (Bronze)
The official description reads: Gave orders 15 times. Again, what it says on the tin and easy enough to get. Using orders is easy. Using orders smartly? Not so much. Sometimes that order may be invaluable, other times it might be better to get another squaddie in there. Think before doing is a good maxim, and this game allows you time to do that in the strategy map.

Martyr's Courage (Bronze)
The official description reads: Make a last stand 15 times. What it says on the tin. A new feature for VC4, Last Stands give a controlled squaddie a chance to either use up their remaining AP and shoot before going critical, or to inspire nearby squaddies on the field. There's a timer for choosing, so you need to decide quick. Generally, taking the action option is better than inspiration, but you have the pro of regaining 1 CP and a stats boost depending on class. Hard call, but situational.

True Rangers (Gold) (Citation needed)
The official description reads: All of your classes were upgraded to max level. This achievement only triggers upon all classes maxing out at Level 30, so get out there and level them up, Commander! And for your efforts, you'll net the Order of the Golden Wings decoration in-game.

The Empire's Worst Nightmare (Gold)
The official description reads: Obtained A ranks on all missions. Yes, ALL missions. Even the Challenge skirmishes. Extra Missions obtained via DLC shouldn't count towards this achievement. You'll get the Peerless Service Medal for your efforts here. Oooh, shiny~!

Ultimate Tank Squad (Gold)
The official description reads: Obtained all tank parts. To do this means fully upgrading the Hafen, Glory and Cactus, as well as developing all parts in R&D and capturing all parts from enemy Aces. You'll also net the Excellence in Technology decoration in-game for your scavenging. Thanks, Godwin!

Arms Racer (Gold)
The official description reads: Obtained all Infantry Weapons. I'm assuming this means at least one of each weapon variant captured from an enemy Ace as well as reward weapons and all R&D weapons. Completing this achievement also nets you the Excellence in Armament decoration..

War Correspondent (Gold)
The official description reads: Viewed all event scenes. This means watching every non-mission scene in the game, in essence. You'll also get the Eastern Theater Service Medal decoration for your troubles..

War Hero (Gold)
The official description reads: Obtained all decorations. Makes you feel good, to be called a War Hero, doesn't it? And you should... since it means you've slogged your guts out to earn every single decoration in the game.

Valkyrian Chronicler (Platinum)
The official description reads: Obtained all achievements. Sounds a little underwhelming, but it's a wonderful feeling when you get this one. It means you've done it all!!

This Section is for Decorations - the in-game medals you can earn. Some have been covered where they tie into achivements, but I'll restate them here as well as their flavour text and triggering conditions. Again, I'll try and keep it spoiler-free.

Krest Service Medal
Given to participants in the battle to capture Fort Krest. Its famously fortified gates adorn the front of this commemorative medal.
Complete Chapter 1 and start Chapter 2. Pretty easy.

Siegval Service Medal
Given to participants in the Battle of Siegval. A depiction of the cliff and its embedded pillboxes adorns this commemorative medal.
Complete Chapter 4 and start Chapter 5. Ties in with the Battle of Siegval achievement.

The Blue Rose
Given for aiding the Resistance in Loweholm. Awarded by the Blue Rose, it is appropriately engraved with a beautiful triad of azure flowers.
Complete Chapter 13 and start Chapter 14. Simple enough.

Federate Medal of Honor
Given to those who exhibit exemplary service in crucial operations. Awarded only once for any given mission, it is known to be a rare award indeed.3
Complete Chapter 16. Note that this medal technically isn't yours, per se... But [redacted for spoilers].

Federation Star of Valor
Given to the officer who contributed most to Operation Cygnus' success. In acknowledgement of its namesake, Cygnus, this medal is star-shaped.
Awarded for completing Chapter 18. Ties in with the Devotion achievement.

Honorary Medal of Valor
Given to a soldier who swayed the tides of battle by defeating an elite officer of the opposing army in combat.
Awarded for killing your first enemy Ace. Note, all Aces are elite officers.

Bronze Medal of Honor
Given to those who have defeated 250 enemies. Recipients of this award earn the respect of their peers, and a place among legendary soldiers.
Defeat 250 enemies in total. Earned on the way to the Agent of Destruction achievement.

Silver Medal of Honor
Given to those who have defeated 500 enemies. It's a rank higher than the Bronze Medal of Honor, and can be awarded multiple times.
Defeat 500 enemies in total. Earned on the way to the Agent of Destruction achievement.

Gold Medal of Honor
Given to those who have defeated 1000 enemies. It is the highest medal of honor one can receive. The V design represents Valor.
Defeat 1000 enemies in total. Earned alongside the Agent of Destruction achievement.

Combat Medic Medal
Given to those who have performed rescues at great personal risk during battle. A depiction of the medic's symbol adorns this medal.
Conduct your first rescue of a squaddie in critical condition.

Deckard Medal
Given to animals that have performed exceptionally on the battlefield. By definition, a human can never receive this award.
This medal is gonna be tricky. You'll need Rags to show up on a medivac mission when you rescue a squaddie. It looks like this will be random chance alone... See note in the Final thoughts re. Training Grounds and be prepared for a lot of hard work on this one. It took me at least ten gos in the one mission. Saving and reloading doesn't improve the odds.

Order of the Golden Wings
Presented to a squad that has reached exceptional levels of skill across all of the soldierly disciplines.
Train all classes up to level 30. This ties in with the True Rangers achievement.

Excellence in Leadership
Given to an officer who has demonstrated remarkable skill as a leader through mastery of the art of command.
Awarded once you have learned all orders. Visit the Mess Hall and do your training, and this one's easy enough.

Excellence in Armament
Presented to a squad that contributed greatly to the development of armament design through their hard work and extensive knowledge.
Obtain all weapons in the game. This includes the Federation Reward weapons and the enemy Ace weapons. Ties in with the Arms Racer achievement.

Excellence in Technology
Presented to a squad that has contributed greatly to the improvement of tanks through their hard work and extensive knowledge.
Obtain all tank parts, including parts from enemy Aces. This ties in with the Ultimate Tank Squad achievement.

Excellence in Teamwork
Presented to a squad that has demonstrated unparalleled skill and teamwork. Each medal has a unique design for the squad it is awarded to.
Fully complete every squaddie's Personnel profile by promoting them to Corporal - which means you'll need to use each of them at least 40CP worth of times. Again, Rhomeo's guide has some useful information on doing this.

Eastern Theater Service Medal
Given to participants of Operation Northern Cross and Operation Cygnus - those who battled across the Eastern Theater until the campaign's end.
Unlocked for completing all Story Battles and viewing all events. Ties in with the War Correspondent achievement.

Meritorious Service Medal
Presented by the Federation to those who have contributed greatly to victory in battle. The Federation flag design adorns this award.
Complete your first A-Rank mission. Possibly complete your first mission in a single turn. It's hard to be certain, but I'm wagering on the latter. Citation needed.

Distinguished Service Medal
Presented by the Federation to those who have displayed exceptional skill and valor. Recipients of this award are considered the best of their battalion.
Complete all missions. Relatively easy, until you get to the Challenge missions.

Peerless Service Medal
The Federation's most prestigious award. Given to the greatest heroes of the Federation - those whose efforts shaped the course of EWII itself.
Complete all missions with an A rank. Feel proud if you get this. Ties in with the War Hero achievement.

Lastly, some general tips for those who have read this guide.

Knowledge is Power
To quote the Blood Ravens of Warhammer 40,000 fame, knowledge is power. Learn what works where and when. Feel free to use earlier Skirmish maps to experiment and test the accuracy of weapons before jumping headlong into missions. Know that researching a weapon in R&D will swap out any non-awarded/looted weapon from soldiers for the newest model of the newest variant, so be sure to check if it's the one you want to use before heading into battle.

Bite the bullet! No pain, no gain!!
Thanks, Sgt. Calvaro Rodriguez for that quote. Accept now that your soldiers WILL die at some point, and while it's ideal to prevent and minimize this, there will be three deaths in your squad, two of them occurring as part of the story. Four if you count someone who's only available post-game. But fear not... After clearing the game, you have the mystical Cenotaph to come to! All you need to do is fondly remember the fallen squaddie and pay a fine in DCT determined by the amount of use they've gotten and they'll be back in action!

Note that in Chapter 16, one of your squaddies WILL die alongside Raz. Both can be regained after set requirements are met. Christel, who also died before Squad F was folded into Squad E, is also available here post-game.

Spend, spend, spend!!
Use that EXP and those DCT early-on and buy the best upgrades you can. You can always earn more, and you shouldn't be saving up stuff for unlockables until post-game at the earliest. It becomes a LOT easier to do that unlockable when you've got the gear for the job. Post-game skirmishes become quite hard, but can earn some huge rewards! However, you're not gonna get anywhere near these if your troops are fighting off Imperial Elites armed with the shiniest new guns from Zechmeister and Von Bismarck if you're using Mk. 1 guns and only relatively primitive armour. How will your squaddies feel knowing they keep getting hurt because their commander is a stingy git? Be a mate - dosh out the dough for your squaddies and you'll find things get a lot easier!

If at first you don't A-rank...
Don't fret. You can always come back and try again later! Some missions it will be impossible to A-Rank on the first go around. The first mission in Chapter 4 and the mission in Chapter 10 are two such examples, as is the irksome mission in Chapter 18. Don't be afraid to focus on learning these maps and how things work, then coming back to try again later. Instead, if you're struggling on these maps, take the time to kill the enemy Aces so you have less to do next time around.

But if you do A-rank...
It never hurts to try again unless you're completely sure you got the Ace. But even then, sometimes it's easier to redo some missions in the hopes of unlocking Squad Stories or even just farming EXP and DCT. It never hurts at all.

Training Grounds
Some Story Battle Maps are better for training certain types of recruits than others. Here are my own recommendations for each class.

Scouts and Snipers - Chapter 2: The Liberation of Reine - Inner City Assault.
This map is especially good for fast-moving scouts to run around and train up since they'll be doing most of the identifying. It's also good since you need to use Snipers to complete the map and take down the Heavy tanks.

Shocktroopers and Lancers - Challenge Skirmish 2: The Dream Team.
A perfect map to build up those CP usage points, since you're facing both Crymaria and Walz on the one map! Use snipers to knock out the Ragnite Crystal in Crymaria's staff to leave her vulnerable, then use Direct Command to hut-two a Shocktrooper into the middle of the area and have the Shocktrooper use their flamethrower. It will take down Crymaria a lot more quickly than bullets. Then, move the Hafen and Glory down along the path to the south of you along with the Lancer you wish to level up. Wait for the Vulcan Procus to come to you along that path. Then, have the Lancer lead the way on shooting, making sure you have the VB PL 5(E) equipped and both tanks in support. Ideally, have your Lancer between the two tanks, all three facing the Vulcan. Use Penetration and Attack Weak Spot on the Lancer, and All Demolish before opening fire. It should only take three or so volleys, but have an Engineer close by for mass reloads if necessary.

Engineers and Grenadiers - Chapter 4: The Battle of Siegval - Breaking the Line 2
I chose this map for training engineers because there's a lot of ladders to repair that you can make use of with skilled engineers to clear the way to the main objective. I'd recommend taking a Shocktrooper and Lancer to support, but all in all, Engineers are gonna be your eyes and ears here - to quote the Company of Heroes US Engineers. Grenadiers also get a lot of fun here with plenty of indirect fire opportunities to be useful and powerful.

Last Stand Grinding: Challenge Skirmish 1 - A True Battlefield
This map is my recommendation because a LOT of damage can get dealt very quickly here. You'll also have all 3 of your vehicles for recovery purposes. Use the Inspire Order on one person, move them forward, and let them eat the machine gun sandwich. Once they go down, if it triggers, use Inspire and pick someone else. Rinse and repeat, making sure to make the rescue each time. I'd recommend leaving your Leaders back and using them as a last-ditch effort.

As a final word... Everything so far published in this guide is going off memory on my own part and some research and theorisation. Anywhere that there's a message on Citation needed or words to that effect means that I'm not 100% certain that my information is correct. Please feel free to post information in the comments if I have erred on details or you wish to provide more details yourself.

I'd also like to thank Rhomeo and ukie for their guides, which have been invaluable in my efforts towards this guide, and especially ukie for their assistance in rounding out the information on the Decorations.

I hope this surprisingly long and exhaustive guide is helpful to you all, commanders. Good hunting!!