U.S. Marines assigned to Alpha Battery, 2d Low Altitude Air Defense Battalion, gather .50-caliber shell casings during Operation Rolling Thunder, at Fort Bragg, N.C., Oct. 18, 2014. The operation was held in order to better integrate the ground combat element with the aviation combat element in support of the Marine Air Ground Task Force. (U.S. Marine Corps photo by Lance Cpl. Koby I. Saunders/Released)