A line of M1A1 Abrams Main Battle Tanks are put into a defensive position during Exercise Desert Scimitar aboard Marine Corps Air Ground Combat Center Twentynine Palms, Calif., April 12, 2015. Desert Scimitar enables 1st Marine Division to test and refine its command and control capabilities and ensures 1st Marine Division units remain committed to consistently improving the quality of their training efforts and their resultant war fighting capabilities.