Chairman of the Joint Chiefs of Staff Admiral Mike Mullen (R) greets Medal of Honor recipient U.S. Army Staff Sgt. (retired) Walter Ehlers (C) as Marine Corps Sergeant Major Joseph Davenport (L) looks on during the medal's 150th Anniversary ceremony in the Hall of Heroes at the Pentagon March 25, 2011 in Arlington, Virginia. During the D-Day invasion of WWII, Ehlers led his unit's attack against German forces and single-handedly defeated several enemy machinegun nests, carried a wounded rifleman to safety, and continued to lead despite his own wounds. With fewer than 90 Medal of Honor recipients still living, about 20 of them attended the ceremony. The medal is presented by the president of the United States for "conspicuous gallantry and intrepidity at the risk of one's life above and beyond the call of duty."