Between July 1958 and October 1960, Bongo was second lieutenant in the French Army of the Air. During this time he earned his baccalaureate (high school diploma) at Brazzaville. While serving as a lieutenant, he was assigned to the Ministry of Foreign Affairs (1960–62). Bongo then served as assistant director of the president's cabinet for seven months and director of the cabinet until 1965. He was subsequently given responsibilities for information and tourism (1963–64) and for national defense (1964–65). In February 1965, a military coup d'état overthrew President Leon Mba. France intervened militarily, however, and restored Mba to power. In September 1965, Bongo was named minister delegate to the presidency, responsible for national defense and coordination. The following year, he was appointed vice president responsible for defense, planning, information, and tourism.
By this time President Mba was gravely ill. He advanced the date for presidential elections and established the post of vice president. In March 1967, national elections were held. Mba was reelected president, and Bongo was elected vice president. On 28 November 1967, Leon Mba died, and Bongo succeeded to the presidency.