Three countries: Tonkin, Cochin China, and Annam.
Huh... just yesterday, youtube suggested I might be interested in the Pathe film news clip of the French parachuting into Dien Bien Phu. Gives a good sense of the terrain. Man, were they really screwed after losing their airfield to the Viet Minh.
Interesting. And then I suppose the French combined them into colonial holding they called Vietnam?