Army Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, prepares to place a wreath at the Tomb of the Unknown Soldier at Arlington National Cemetery in Arlington, Va., Sept. 25th, 2015. Dempsey laid the wreath to honor unknown service members as he prepares to retire after 41 years of service. U.S. Army photo by Spc. Cody W. Torkelson