Airmen from the 13th Air Support Operations Squadron cross the Arlington National Bridge en route to Arlington National Cemetery to honor a fallen comrade Maj. David Gray by completing the “DG” 140, Aug. 8, 2013. “DG” 140 is a 140-mile memorial ruck march for Maj. David Gray, beginning at the Casualty Reception Center at Dover Air Force Base, Del., to Gray’s headstone at Arlington National Cemetery, Aug 4-8. (U.S. Air Force photo/Senior Airman Carlin Leslie)