Secretary Gates shares a laugh with Gen. Peter Pace. Secretary of Defense Robert M. Gates (right) shares a laugh with Chairman of the Joint Chiefs of Staff Gen. Peter Pace, U.S. Marine Corps, in Gatesí office in the Pentagon on Sept. 27, 2007, Pace's last day as chairman. Pace will retire on Sept. 30, 2007, after more than 40 years of service. The next chairman will be Adm. Mike Mullen, U.S. Navy. Mullen will be sworn in on Oct. 1, 2007. SHARE: Download: Full Size (0.03 MB) Credit: VIRIN: 387520-O-OZT82-387.jpg Photo Gallery