Author: Liu Tiejun
History of the Federation of French Indochina:
The French invasion of Southeast Asia began in September 1858, when French troops, aided by Spain, attacked the Vietnamese port cities of Da Nang and Saigon during the Nguyen Dynasty. In 1863, King Norodom of Cambodia was forced to submit his kingdom to France as a protectorate. A series of expansions in French territory in the following years led to the formation of French Indochina in 1887 as a colonial union, the Federation of French Indochina. Originally it included what is now Vietnam and Cambodia, with its capital in Saigon, Jiaotongina. After the French army defeated Siam in 1893, Laos joined the Federation. In 1899, the Guangzhou Bay Treaty Port in southern China was forcibly leased by France and placed under the jurisdiction of French Indochina. In 1902, the capital of the Federation of French Indochina was moved to Hanoi. Additional territory was acquired from Siam in the early 1900s.

(Flag of French Indochina)
The coastal areas of the Federation of French Indochina provided tea, rice, coffee, pepper, coal, zinc, tin and rubber to the French Empire, while the inland areas, the Laos region, provided some wood; especially rubber, which increased the value of French Indochina, especially after the increase in the use of automobiles. Saigon was the main transportation and commercial center of French Indochina and by 1937 was the sixth busiest port in the entire French Empire. The Trans-Indochina Railway, which connects Hanoi and Saigon, opened in 1936. French Indochina has about 7,784,000 people in Tokyo, about 8,000,000 people in Annan, about 4,484,000 people in Jiaotongia, about 3,000,000 people in Cambodia, and about 1,300,000 people in Laos, for a total of about 24,568,000 people.
French Federation of Indochina in World War II:
In the European War, France was defeated by Germany. France (i.e., Vichy France) weakened significantly, trying to remain non-belligerent in the ongoing conflict, with little success. In June 1940, the Japanese military requested and was granted permission to establish a military mission in Tokyo, Vietnam. In August 1940, Japan further demanded the right to use airports in other parts of French Indochina, and France has been delaying negotiations. On September 5, due to repeated delays, the Japanese invaded French Indochina. The French admitted defeat on September 25, 1940, beginning a period when French Indochina remained nominally French dependency and the Japanese held real power behind the scenes. In October 1940, the Thai army took advantage of the situation to provoke French Indochina and escalated into the Franco-Thai War. The Japanese intervened and negotiated, and Thailand regained territory it had occupied by France in the early 1900s. Japan's aggression against French Indochina became the last straw in the United States' decision to ban the export of strategic goods to Japan. The whole of French Indochina played an important role in the early days of World War II, as it cut off China's supply routes. When the Pacific War broke out in December 1941, Jiaotong Indochina became the starting point for Japanese invading forces to travel to British Malaya.
(Japanese warships stationed in French Indochina were attacked by U.S. forces.)
Japan used French puppets to control three colonies in Vietnam until March 9, 1945, when the Japanese took direct control of Indochina. Americans and Chinese supported the Vietnamese (Vietnamese Independent Association) resistance movement in French Indochina, which had Communists but did not adhere to communist philosophy. Soon after, the Soviet Union also became a staunch supporter. By 1944, viet minh had 500,000 members, of which 200,000 were in Tokyo, Vietnam, 150,000 in Annan and 150,000 in Jiaotongina. After the war, captured Japanese weapons and facilities were handed over to the Viet Minh. The defeat of the common enemy led to the division of all factions in society, and each faction of Vietnam declared its independence. The return of the French did not unite the movements. In the end, the communist faction under Ho Chi Minh will triumph in the coming decades.
Throughout the war, Cambodia was occupied by about 8,000 Japanese troops. The French nominally controlled Cambodia until March 9, 1945, when King Norodom Sihanouk declared the kingdom of Cambodia independent with the support of Japan. After World War II, the French colonial government returned to Cambodia. When French Indochina disintegrated in 1953, Cambodia would gain independence and King Norodom Sihanouk would remain its monarch until 1955 (he would be the leader to remain influential for decades to come).
Laos was influenced by Japan and Thailand during the war. Several resistance movements formed during this period, including one supported by the French. On April 8, 1945, King Si sawang declared the nominal independence of Laos; Crown Prince Sawang watttana would soon travel to the mountains to organize another anti-Japanese movement. After the war, King Sishawan willingly returned to French rule, which sparked a brief power struggle with the Lao Isala nationalists. King Sisawan returned to power in April 1946. Laos will gain independence after the end of French Indochina in 1953, and King Sisawang will remain monarch until his death in October 1959.
During the war years, a total of 1,000,000 to 2,000,000 people died in French Indochina, most of them from famine and Japanese abuse.
After World War II, China and The British occupied French Indochina on the 16th parallel north, and the Canton Bay lease was returned to China. Subsequently, the French returned to French Indochina with the support of Britain and the United States, taking over French Indochina from Chiang Kai-shek's army and British troops.