 The defeat of the French Army at Điện Biên Phủ in 1954 , followed by the Geneva Accords , led to a divided Vietnam . The French @-@ backed State of Vietnam , led by former Emperor Bảo Đại , provisionally held control south of the 17th parallel . Hồ Chí Minh 's Viet Minh held the north under the Democratic Republic of Vietnam , which Hồ Chí Minh had proclaimed in 1945 . The agreements stated that nationwide elections were to be held in 1956 to unify the country under a common government . In July 1954 , during the transition period , Bảo Đại appointed Diệm as Prime Minister of the State of Vietnam . 
