LAST LESSON U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, gives the 582 senior military officers a last lesson in leadership during commencement ceremonies at the National Defense University, Fort Leslie J. McNair, Washington, D.C., June 11, 2009. SHARE: Download: Full Size (0.04 MB) Credit: VIRIN: 069224-T-QNO04-188.jpg Photo Gallery