The United States Marine Corps has four divisions, including the 1st Marine Division, the oldest and largest active duty division in the United States Marine Corps, headquartered at Marine Corps Base Camp Pendleton, Calfornia.
The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combined arms, implementing its own infantry, armor, artillery, aerial and special operations forces. The Marine Corps fulfills a critical military role as an amphibious warfare force. 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 oldest and largest active duty division in the United States Marine Corps, representing a combat-ready force of more than 19,000 men and women. Marine Corps Base Camp Pendleton It is one of three active duty divisions in the Marine Corps today and is a multi-role, expeditionary ground combat force. Marine Corps Base Camp Pendleton is the major West Coast base of the United States Marine Corps and is one of the largest Marine Corps bases in the US. It is on the Southern California coast, in San Diego County, and bordered by Oceanside to the south, Cleveland National Forest, San Clemente, and Orange County to the north, Riverside County to the northeast, and Fallbrook to the east. The I Marine Expeditionary Force ("I" pronounced "One") is a Marine Air Ground Task Force (MAGTF) of the United States Marine Corps primarily composed of the 1st Marine Division, 3rd Marine Aircraft Wing, and 1st Marine Logistics Group. 
