Which 1954 battle ended in a major French defeat in Vietnam?

Which 1954 battle ended in a major French defeat in Vietnam? The answer is Dien Bien Phu.

The Battle of Điện Biên Phủ was a decisive French defeat in the First Indochina War. Fought from March 13 to May 7, 1954, it pitted a French Union garrison against Viet Minh forces commanded by General Võ Nguyên Giáp in northwestern Vietnam.

France established the base in a valley near Laos to block Viet Minh supply routes and lure the opposing army into a major battle. Instead, the Viet Minh moved artillery and large numbers of troops through difficult terrain, surrounded the position and subjected it to sustained attacks.

The garrison surrendered after 57 days of fighting. The defeat badly damaged French political will and strengthened the Viet Minh’s position at the Geneva Conference, where the future of Indochina was negotiated. It contributed directly to the end of French colonial rule and the temporary partition of Vietnam.

The battle is often confused with later Vietnam War engagements such as Ap Bạc, Ia Drang and Khe Sanh. Those battles involved the divided Vietnamese states and, in varying ways, U.S. forces; Điện Biên Phủ primarily concluded the French-Viet Minh conflict.