U.S. Marine Corps Lance Cpl. Erick Perez, left, and Lance Cpl. Cain Roth, right, with 1st Combat Engineer Battalion, help build a terrain model of Marine Corps Air Ground Combat Center Twentynine Palms aboard Camp Pendleton, Calif., Apr. 23, 2014. The terrain model was constructed for the commanding general of 1st Marine Division, Major Gen. Lawrence D. Nicholson, for the Rehearsal of Concept Brief of Exercise Desert Scimitar. (U.S. Marine Corps photo by Lance Cpl. Brandon Martinez, 1st Marine Division Combat Camera/Released)