The Battle of Dien Bien Phu was a climactic confrontation of the First Indochina War that took place between 13 March and 7 May 1954. It was fought between the French Union's colonial Far East Expeditionary Corps and Viet Minh communist revolutionaries. The United States was officially not a party to the war, but it was secretly involved by providing financial and material aid to the French Union, which included CIA contracted American personnel participating in the battle. The People's Republic of China and the Soviet Union similarly provided vital support to the Viet Minh, including most of their artillery and ammunition.