Marines with Combined Anti-Armor Team 2, 1st Battalion, 7th Marine Regiment, adjust their principal directions of fire on their weapon systems during a defensive exercise here, Oct. 15, 2013. The battalion conducted a three-day defense to practice developing proper fields of fire, establishing fighting positions and challenging Marines' ability to operate while sleep deprived. The Marines also created numerous range cards, which are rough sketches of a fighting position that identify gunfire lateral limits, principal directions of fire and possible enemy locations.