U.S. Army Soldiers from the Headquarters and Headquarters Battery, 3rd Battalion, 13th Field Artillery Regiment, attached to the 2nd Brigade Combat Team, 1st Infantry Division, rehearse fire missions during Decisive Action Rotation 15-06 at the National Training Center, Fort Irwin, Calif., March 25, 2015. Decisive Action Rotations allow units to fully exercise their Mission Essential Task List that supports the Army's core competencies: Wide area security and combined arms maneuver. (U.S. Army photo by Spc. Ashley Marble/Released)