On September 25th, 1942, President Franklin D. Roosevelt dedicated Camp Pendleton in a special tribute to World War I. The 125,000 acre site would be the largest Marine Corps base in the country and was necessary as the only other training bases at the time were Quantico, VA, Parris Island, SC, and San Diego.

The base was named for Major General Joseph Henry Pendleton. Aside from being a huge advocate for a West Coast base of its nature, Maj. Gen. Pendleton was Naval Academy graduate-turned Marine Corps officer with 40 years of experience during his military career. His stars were earned in engagements such as the Spanish-American War, the Philippine-American War, and the Banana Wars (Central America and Mexico). He would become the Mayor of Coronado, CA, after his retirement from the military.

During World War II, Camp Pendleton was home to numerous training schools for landing craft, amphibious vehicles and communication, beach battalions, and medical field services. The base expanded through the Korean War with over $20 million in renovations and trained 200,000 Marines through the Korean and Vietnam wars. In 1975, it was the first military base to house over 50,000 Vietnamese refugees in one of the largest humanitarian efforts of its kind.

The 1980s saw Pendleton's mission expand from amphibious to expeditionary, and soon troops there could deploy halfway around the world in only a few days. This would greatly benefit the Marines in many upcoming and current conflicts. In 2005, it became one of only five DoD locations for the Standard Terminal Automation Replacement System (STARS) brand new air traffic control radar system.

Camp Pendleton is primarily home to The I Marine Expeditionary Force. It is comprised of 1st Marine Division, 3rd Marine Aircraft Wing, 1st Marine Logistics Group, 11th, 13th and 15th Marine Expeditionary Units, the MEF Headquarters Group, 1st Air Naval Gunfire Liaison Company and the 1st Marine Expeditionary Brigade.

The I Marine Expeditionary Force is Air-Ground Task Force that was designated in Okinawa, Japan on November 8th, 1969. Just a little over a year later, it was redesignated I Marine Amphibious Force, before being relocated to Camp Pendleton in April of 1971. I Marine Expeditionary Force has seen numerous theaters of war including Operation Desert Storm, Operation Enduring Freedom, and 2003 Invasion of Iraq, Operation Vigilant Resolve, and Operation Phantom Fury that were part of Operation Iraqi Freedom

Other commands on base include: Marine Corps Installations-West, 1st Marine Special Operations Battalion, Marine Corps Tactical Systems Support Activity, Wounded Warrior Battalion West, Marine Corps Recruit Depot San Diego's Weapons & Field Training Battalion, Marine Corps and Army Reserve Forces, Navy's Assault Craft Unit 5, Naval Hospital Camp Pendleton, and the 1st Dental Battalion.

Army and Marine reserves also utilize the base for training and other relevant capacities. 42,000 active duty personnel reside on base, with 77,000 retired veterans living inside the 50-mile radius of the Camp.