In 1941, the Viet Minh  — a communist and nationalist liberation movement  — emerged under Ho Chi Minh, to seek independence for Vietnam from France as well as to oppose the Japanese occupation. An estimated 2 million Vietnamese, or 10% of the population then, died during the Vietnamese famine of 1944–45. Following the military defeat of Japan and the fall of its Empire of Vietnam in August 1945, Viet Minh occupied Hanoi and proclaimed a provisional government, which asserted independence on 2 September.

In the same year the Provisional French Republic sent the French Far East Expeditionary Corps, which was originally created to fight the Japanese occupation forces, in order to pacify the liberation movement and to restore French rule. On November 20, 1946, triggered by the Haiphong Incident, the First Indochina War between Viet Minh and the French forces ensued, lasting until 20 July 1954.

Despite fewer losses — Expeditionary Corps suffered one-third the casualties of the Chinese and Soviet-backed Viet Minh — during the course of the war, the French and Vietnamese loyalists eventually suffered a major strategic setback at the Siege of Dien Bien Phu, which allowed Ho Chi Minh to negotiate a ceasefire with a favorable position at the ongoing Geneva conference of 1954. Colonial administration ended as French Indochina was dissolved. According to the Geneva Accords of 1954 the forces of former French supporters and communist nationalists were separated south and north, respectively, with the Vietnamese Demilitarized Zone, at the 17th parallel north, between.

A Partition of Vietnam, with Ho Chi Minh's Democratic Republic of Vietnam in North Vietnam, and Emperor Bao Dai's State of Vietnam in the South Vietnam, was not intended by the 1954 Agreements, and they expressly forbade the interference of third powers. Counter to the counsel of his American advisor, the State of Vietnam Prime Minister Ngo Dinh Diem toppled Bao Dai in a fraudulent referendum organised by his brother Ngo Dinh Nhu, and proclaimed himself president of the Republic of Vietnam. The Accords mandated nationwide elections by 1956, which Diem refused to hold, despite repeated calls from the North for talks to discuss elections.