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

A U.S. Marine with 1st Battalion, 6th Marine Regiment, 2nd Marine Division (MARDIV), participates in a knot tying class prior to the start of Mountain Exercise 5-15 at the Marine Corps Mountain Warfare Training Center, Bridgeport, Calif., Sept. 2, 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)