SERENE WALK In his final full day as the 17th chairman of the Joint Chiefs of Staff, Navy Adm. Mike Mullen and his wife, Deborah, walk through Arlington National Cemetery's Section 60, Sept. 29, 2011. Mullen will retire after serving more than 40 years in uniform, handing the reins to Army Gen. Martin E. Dempsey during a ceremony on Fort Meyer, Va. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 380103-T-IDE82-309.jpg Photo Gallery