Gia Long born Nguyen Phuc Anh was an emperor of Annam born about the half of the 18th century and died in 1820. He founded the Nguyen Dynasty, the last of the Vietnamese dynasties before the revolution.

His uncle Phuc Tuan (Dul Tung) lost his throne as feudal lord of southern Vietnam during the Tay Son peasant rebellion led by the brothers Nguyen Hue, Nguyen Nhac and Nguyen Lu in 1777. Nguyen Anh was the only member of the Nguyen family that survived the Tay Son victory in 1777. Anh fled to Thailand and returned later with a Thai army in an attempt to restore himself to power by force in 1785. He was defeated by Nguyen Hue and forced to go into hiding again. On Phu Quoc island he was helped by the French priest Pigneau de Behaine , who helped Anh make an alliance with the French King Louis XVI to help him take control of Vietnam.

With the help of Behaine, Anh gained many French mercenaries, modern western weapons, naval ships and French military advisors to teach his troops. He returned to Vietnam, taking Saigon in 1788, Qui Nhon in 1799, Hue in 1801 and finally the capital of Hanoi in 1802.

In June 1802 was proclaimed Emperor with the name of Gia Long and was recognized by China in 1804. He moved the capital to the Nguyen city of Hue and named the country "Nam Viet", which was changed by the Chinese to the modern name "Viet Nam". To his enemies, Gia Long was typically cruel, having them tortured, the bodies of their dead ancestors desecrated before them and executed; but to his friends he was very rewarding. He generally tolerated foreign presence in Vietnam and gave many of his French supporters high offices and titles in Vietnam. He also built the Mandarin's Road and abolished all of the reforms made by the Tay Son, reverting back to the Confucian monarchy copied from the days of Ming China. His legal code was almost a total copy of that used by the Qing Dynasty in China at that time. The new capital city, protocol and court dress were all taken directly from Ming dynasty styles. He also continued to have trouble with dispersed peasant revolts and claimants to the former Le Dynasty claiming the throne. These events also caused him to turn against the foreign presence in Vietnam in his final years.