A U.S. Marine with 1st Battalion, 6th Marine Regiment,

A U.S. Marine with 1st Battalion, 6th Marine Regiment, 2nd Marine Division (MARDIV), leads his pack mule to a stream during a rest period before transporting crew served weapons to the Forward, where the battalion has their front line defense for Mountain Exercise 5-15 at the Marine Corps Mountain Warfare Training Center, Bridgeport, Calif., Sept. 22, 2015. Marines participate in a month-long field exercise focusing on core mission essential tasks such as assault climbing, animal packing and small unit movements, to strengthen expeditionary high altitude warfare tactics in a mountainous environment against a hybrid threat, as they prepare for world-wide deployment. (U.S. Marine Corps photo by Cpl. Kelly L. Street, 2D MARDIV COMCAM/Released)