President Barack Obama attends the chairman change of responsibility ceremony on Joint Base Myer-Henderson Hall in Arlington, Va., Sept. 25, 2015. During the ceremony, Army Gen. Martin E. Dempsey, outgoing chairman of the Joint Chiefs of Staff, retired from the military after 41 years of service and was succeeded as chairman by Marine Corps Gen. Joseph F. Dunford Jr. DoD photo by D. Myles Cullen