The 1st Marine Division (1st MARDIV) is a Marine infantry division of the United States Marine Corps headquartered at Marine Corps Base Camp Pendleton, California. It is the ground combat element of the I Marine Expeditionary Force (I MEF). Headquarters Battalion. "Standard Bearers". 1st Marine Division, Camp Pendleton, Calif. 1st MARDIV Command Duty Officer. Headquarters Building. Call: () . 1st Marine Division COMMSTRAT Office. For any issues regarding media or. Fletcher 's Task Force It spent the duration of World War I in Cuba and was disbanded after the war. The battalion shares the San Mateo 62 Area with 5th Marines. By June, the entire division was in South Vietnam. The greater part of the PVA 9th Army was rendered ineffective as they suffered an estimated 37, casualties trying to 1st marine division address the Marines' march out of the "Frozen Chosin".