Multiple choice France suffered defeat by the Viet Minh in 1954 at... Dien Bien Phu My Lai Saigon The Gulf of Tonkin Reveal answer Fill a bubble to check yourself A Correct answer Explanation The Battle of Dien Bien Phu in 1954 was a decisive victory for the Viet Minh against the French colonial forces. This defeat effectively ended French involvement in Indochina.