1st Battalion, 1st Marines

U.S. Marines with 1st Battalion, 1st Marine Regiment, 1st Marine Division, hike through a simulated chemical attack at Marine Corps Base Camp Pendleton, California, Jan. 12, 2019. Marines trained in extreme environments in order to achieve maximum lethality during the intensity of future deployments. (U.S. Marine Corps photo by Cpl. Rhita Daniel)

U.S. Marines from 1st Battalion, 1st Marine Regiment, 1st Marine Division hike through a simulated chemical attack at Marine Corps Base, Camp Pendleton, California, Jan. 12, 2019. Marines train in extreme environments in order to achieve maximum lethality during the intensity of war. (U.S. Marine Corps photo by Cpl. Rhita Daniel)

U.S. Marines with 1st Battalion, 1st Marine Regiment, 1st Marine Division, hike through a simulated chemical attack at Marine Corps Base Camp Pendleton, California, Jan. 12, 2019. Marines trained in extreme environments in order to achieve maximum lethality during the intensity of future deployments. (U.S. Marine Corps photo by Cpl. Rhita Daniel)

Marines from 1st Battalion, 1st Marine Regiment, prepare for a rapid fire on the enemy target during an individual training exercise at Range 410A aboard the Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., July 25, 2017. 1/1 is based out of Marine Corps Base Camp Pendleton, Calif., and is serving as part of the GCE during ITX 5-17. (U.S. Marine Corps photo by Pfc. Margaret Gale)

Cpl. Christopher Stephens, mortarman, 1st Battalion, 1st Marine Regiment, prepares rounds for Pfc. Thomas Curtis, mortarman, 1/1, during an individual training exercise at Range 410A aboard the Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., July 25, 2017. 1/1 is based out of Marine Corps Base Camp Pendleton, Calif. and is serving as part of the GCE during ITX 5-17. (U.S. Marine Corps photo by Pfc. Margaret Gale)

Lance Cpl. Kyle Hollenback, mortarman, 1st Battalion, 1st Marine Regiment, loads a while Pfc. Sean Carlson, mortarman, 1/1, stabilizes the stand during an individual training exercise at Range 410A aboard the Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., July 25, 2017. 1/1 is based out of Marine Corps Base Camp Pendleton, and is serving as part of the GCE during ITX 5-17. (U.S. Marine Corps photo by Pfc. Margaret Gale)

Cpl. Blake Arnold, forward observer, mortarman, 1st Battalion, 1st Marine Regiment, calculates the target coordinates during an individual training exercise at Range 410A aboard the Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., July 25, 2017. 1/1 is based out of Marine Corps Base Campy Pendleton, Calif., and is serving as part of the GCE during ITX 5-17. (U.S. Marine Corps photo by Pfc. Margaret Gale)