U.S. Marine Corps Sgt. John C. Joyner, an instructor

U.S. Marine Corps Sgt. John C. Joyner, an instructor with Weapons and Field Training Battalion, demonstrates how to assemble a gas mask Sept. 19, 2017, on Parris Island, S.C. Field training instructors, like Joyner, 26, from Gilbert, S.C., are responsible for teaching recruits how to properly use the gas mask and ensuring they can use it properly while inside the gas chamber. Mike Company is scheduled to graduate Nov. 10, 2017. Parris Island has been the site of Marine Corps recruit training since Nov. 1, 1915. Today, approximately 19,000 recruits come to Parris Island annually for the chance to become United States Marines by enduring 13 weeks of rigorous, transformative training. Parris Island is home to entry-level enlisted training for approximately 50 percent of male recruits and 100 percent of female recruits in the Marine Corps. (U.S. Marine Corps photo by Lance Cpl. Joseph Jacob)