The Vietnam Revolutionary League (Vietminh) was established by Ho Chi Minh while living in China on the Vietnam border.

In September, 1940, the Japanese army invaded Indochina. With Paris already occupied by Germany, the French troops decided it was not worth putting up a fight and they surrendered to the Japanese. Ho Chi Minh and his fellow nationalists saw this as an opportunity to free their country from foreign domination. Under the military leadership of General Vo Nguyen Giap, the Vietminh began a guerrilla campaign against the Japanese.

The Vietminh received weapons and ammunition from the Soviet Union, and after the bombing of Pearl Harbour, they also obtained supplies from the United States. During this period the Vietminh leant a considerable amount about military tactics which was to prove invaluable in the years that were to follow.

When the Japanese surrendered to the Allies after the dropping of atom bombs on Hiroshima and Nagasaki in August, 1945, the Vietminh was in a good position to take over the control of the country.