The First Indochina War began in French Indochina on 19 December 1946, and lasted until 1 August 1954. Fighting between French forces and their Viet Minh opponents in the south dated from September 1945. The conflict pitted a range of forces, including the French Union's French Far East Expeditionary Corps, led by France and supported by Bảo Đại's Vietnamese National Army against the Viet Minh, led by Ho Chi Minh and the People's Army of Vietnam led by Vo Nguyen Giap. Most of the fighting took place in Tonkin in northern Vietnam, although the conflict engulfed the entire country and also extended into the neighboring French Indochina protectorates of Laos and Cambodia.
At the Potsdam Conference in July 1945, the Combined Chiefs of Staff decided that Indochina south of latitude 16° north was to be included in the Southeast Asia Command under British Admiral Mountbatten. Japanese forces located south of that line surrendered to him and those to the north surrendered to Generalissimo Chiang Kai-shek. In September 1945, Chinese forces entered Tonkin and a small British task force landed at Saigon.