According to Francois Forestier, a film writer for L'Express magazine in Paris, the first time a Vietnam veteran made a movie about the war, the story concerned a much earlier conflict--the Indochina war that the French army lost to the Viet Minh.
The French-language film was "The 317th Section" by Pierre Schoendoerffer, a French army combat cameraman captured when Dienbienphu fell to Ho Chi Minh's forces in 1954. The movie was about a platoon lost in the jungle after escaping from that shell-battered bastion.
The movie was released in 1964. Three years later, Forestier says, Schoendoerffer made a second film about a second war in the same country. Called "The Anderson Section," it was about a black soldier leading a platoon. The platoon was part of the U.S. Army and it was fighting the new version of the Viet Minh--the Viet Cong.