French Indochina was a federation of French colonies and protectorates in Southeast Asia, part of the French colonial empire. It consisted of Cochin China, Tonkin, Annam, Laos and Cambodia.
France assumed sovereignty over Annam and Tonkin after the Franco-Chinese War (1884–1885). French Indochina was formed in October 1887, from Annam, Tonkin, Cochin China, and the Kingdom of Cambodia; Laos was added in 1893. The federation lasted until 1954. The capital of French Indochina was Hanoi. The French formally left the local rulers in power (Emperors of Vietnam, Kings of Cambodia, Kings of Luang Prabang), but in fact gathered all powers in their hands, the local rulers acting only as figureheads.
In September 1940, during World War II, Vichy France granted Japan’s demands for military access to Tonkin. Immediately, this allowed Japan better access to China in the Sino-Japanese War, against the forces of Chiang Kai-shek, but it was also part of Japan’s strategy of domination of the Pacific Ocean, helped greatly by the success of its ally Germany in defeating Pacific powers the Netherlands and France. The Japanese kept the French bureaucracy and leadership in place to run French Indochina.
On March 9, 1945, with France liberated, Germany in retreat, and the USA ascendant in the Pacific, Japan decided to take complete control of French Indochina. The Japanese kept power until the news of their government’s surrender came through in August, after the atomic bombs were dropped on Hiroshima and Nagasaki.
After the war, France attempted to reassert itself in the region, but came into conflict with the Viet Minh, an organization of Communist Vietnamese nationalists under French-educated Ho Chi Minh. During World War II, the USA had supported the Viet Minh in resistance against the Japanese; the group was in control of the country apart from the cities since the French gave way in March 1945. After persuading Emperor Bao Dai to abdicate in his favor, on September 2, 1945, Ho, as president, declared independence for the Democratic Republic of Vietnam. But before the end of September, a force of British, French and Indians, who also pressed captured Japanese into service, restored French control. Bitter fighting ensued in the First Indochina War. In 1950, Ho again declared an independent Democratic Republic of Vietnam, which was recognized by the fellow Communist governments of China and the Soviet Union.
Fighting lasted until March 1954, when the Viet Minh won the decisive victory against French forces at the grueling Battle of Dien Bien Phu. This led to the partition of Vietnam into North, under Viet Minh control, and South, called the Republic of Vietnam, which had the support of the USA, the United Kingdom, and France. The events of 1954 also marked the end of French involvement in the region, and the beginnings of serious US commitment to South Vietnam which led to the Vietnam War.
The partition was agreed to at the Geneva Conference, where the United States of America, the Soviet Union, the United Kingdom, France and the People’s Republic of China also settled a number of outstanding disputes relating to the Korean War. It was at this conference that France relinquished any claim to territory in the Indochinese peninsula. Laos and Cambodia also became independent in 1954, but were both drawn into the Vietnam War.