The event that marked the end of French colonial rule in Indochina was the Batlian of Dien Bien Phu in 1954. This decisive battle resulted in a significant defeat for French forces against the Viet Minh, a communist-led resistance. The outcome prompted international negotiations leading to the Geneva Accords and the temporary partition of Vietnam into North and South. This shift not only ended French colonial ambitions in the region but also set the stage for the subsequent involvement of the United States and the Vietnam War.