The First Indochina War began in French Indochina on December 19, 1946, and lasted until July 20, 1954. Fighting between French forces and their Việt 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 the government of France and supported by the former emperor Bảo Đại's Vietnamese National Army against the People's Army of Vietnam and Việt Minh, led by Võ Nguyên Giáp and Hồ Chí Minh. 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. The 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 city of Saigon.