NEW CHAIRMAN Army Gen. Martin E. Dempsey delivers remarks during the chairman of the Joint Chiefs of Staff change of responsibility ceremony at Summerall Field, Joint Base Myer-Henderson Hall, Va., Sept. 30, 2011. Dempsey, the18th chairman of the Joint Chiefs of Staff, succeeded Navy Adm. Mike Mullen, outgoing chairman, during the ceremony. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 679337-H-RTU54-011.jpg Photo Gallery