TURRET DUTY A Marine mans a turret on an assault amphibious vehicle during a mechanized raid in support of Exercise Steel Knight 2014 at Marine Corps Air Ground Combat Center Twentynine Palms, Calif., Dec. 13, 2013. The assault utilized both air and ground elements to eliminate their objective. Steel Knight is an annual exercise that includes elements from the entire I Marine Expeditionary Force. SHARE: Download: Full Size (0.04 MB) Credit: VIRIN: 980541-A-JQL91-703.jpg Photo Gallery