U.S. Secretary of Defense Robert M. Gates (right) shakes hands with Spc. Shawn M. Mason, a military police officer with Headquarters and Headquarters Company, Brigade Special Troops Battalion, 4th Advise and Assist Brigade, 3rd Infantry Division, United States Division - Center, and a Harrisburg, Pa., native, after pinning the Purple Heart on his uniform Sept. 1 at Camp Ramadi, Iraq. Mason was awarded the Purple Heart for injuries he suffered when his vehicle was struck by a RKG-3 grenade Aug. 9 near Fallujah, Iraq.