Secretary Gates addresses the audience during an assumption of command ceremony. Secretary of Defense Robert M. Gates addresses the audience during an assumption of command ceremony at MacDill Air Force Base, Fla., on Aug. 11, 2010. During the ceremony, presided over by Gates, outgoing acting commander of U.S. Central Command Lt. Gen. John Allen handed over command to Gen. James N. Mattis. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 143168-U-NFJ30-462.jpg Photo Gallery