In August 1945, the Japanese surrendered to the Allies, creating a power vacuum in Vietnam. The Viet Minh launched the "August Revolution" across the country to seize government offices. Emperor Bao Dai abdicated on August 25, 1945, ending the Nguyen Dynasty. On September 2, 1945 Ho Chi Minh declared Vietnam independent under the new name of Democratic Republic of Vietnam (DRV) and held the position of Chairman.

In southern Vietnam, British forces landed in Saigon to disarm the Japanese, followed by French troops trying to re-establish their rule. In the north, Chiang Kai-shek's army entered Vietnam, also to disarm the Japanese, followed by the forces of the non-Communist Vietnamese parties, such as Viet Nam Quoc Dan Dang and Viet Nam Cach Mang Dong Minh Hội. In 1946, Vietnam had its first National Assembly election, which drafted the first constitution, yet its situation was very precarious: the French tried to regain power by force; some Cochin-Chinese politicians formed a seceding government of Cochin-China (Nam Kỳ Quốc); the non-Communist and Communist forces were killing each other. Stalinists purged Trotskyists. Religious sects and resistance groups formed their own militias. The Communists eventually suppressed all non-Communist parties but failed to secure a peace deal with France.

In 1947, full scale war broke out between Viet Minh and France. Realizing that colonialism was coming to an end worldwide, France fashioned a semi-independent State of Vietnam, within the French Union, with Bảo Đại as Head of State. Meanwhile, as the Communists under Mao Zedong took over China, Viet Minh began to receive military aid from China. Beside supplying materials, Chinese cadres also pressured the Vietnamese Communist Party, then under First Secretary Truong Chinh, to emulate their brand of revolution, unleashing a purge of "bourgeois and feudal" elements from the Viet Minh ranks, carrying out a ruthless and bloody land reform campaign, and denouncing "bourgeois and feudal" tendencies in arts and literature. Many true patriots and devoted Communist

The Việt Minh force grew significantly with China's assistance and in 1954, under the command of General Vo Nguyen Giap, launched a major siege against French bases in Dien Bien Phu. The Viet Minh force surprised Western military experts with their use of primitive means to move artillery pieces and supplies up the mountains surrounding Điện Biên Phủ, giving them a decisive advantage. On May 7 1954, French troops at Dien Bien Phu, under Christian de Castries, surrendered to Viet Minh. On July 1954, the Geneva Accord was signed between France and Viet-Minh, paving the way for France to leave Vietnam.