REHEARSAL FIRE Marine Corps Lance Cpl. Nick Grasso, left, and Marine Corps Lance Cpl. Vincent Crisomia fire their M252 81 mm mortar system during Exercise Steel Knight 2014 on Marine Corps Air Ground Combat Center Twentynine Palms, Calif., Dec. 12, 2013. The annual exercise enabled the Marines to refine and rehearse essential combat skills needed in a combat environment. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 292520-S-XGJ19-863.jpg Photo Gallery