Minh Mạng (Hán tự: 明命; 1791–1841; born Nguyễn Phúc Đảm 阮福膽, also known as Nguyễn Phúc Kiểu 阮福晈) was the second emperor of the Nguyễn Dynasty of Vietnam, reigning from 14 February 1820 until 20 January 1841. He was a younger son of Emperor Gia Long, whose eldest son, Crown Prince Cảnh, had died in 1801. He was well known for his opposition to French involvement in Vietnam and his rigid Confucian orthodoxy. As Gia Long aged, he took on a more isolationist foreign policy, and as a result favored Minh Mạng especially for his outlook. Minh Mạng was a classicist who was regarded as one of Vietnam's most scholarly monarchs. He was known as a poet and was regarded as an emperor who cared sincerely about his country and paid great attention to its rule, to the extent of micromanaging certain policies. He pursued a sceptical policy to Christian missionaries, often trying to inhibit their activities by administrative means, and later by explicitly banning proselytisation. His crackdowns led to negative European sentiment towards Vietnam and fomented discontent among Catholics at home and abroad which further antagonised Western attitudes towards Vietnam. The Christian West tried to forbade the growth and transfer of science and technology to Vietnam and in time its military in particular became antiquated. At home he strengthened the central administration and had to contend with several rebellions. The most serious came in 1833 when southern Vietnam revolted, leading to a civil war lasting a year. This was further deepened by an invasion into the same area by Siamese forces who had attempted to retake Cambodia from Vietnam. After a long struggle, his forces managed to put down both enemies and regain control.