In April 1983, the Commandant of the Marine Corps approved the original Marine Air-Ground Task Force (MAGTF) Headquarters concept, providing the sourcing for two Marine Amphibious Unit (MAU) headquarters.

The Commandant directed the establishment of two additional MAU headquarters in November 1985. As a result, the Headquarters of the 15th MAU was activated July 1, 1987, on Marine Corps Base Camp Pendleton, California.

The Commandant directed the replacement of the title "Headquarters" with "Command Element" in the titles of the MAGTFs in August 1987. The 15th MAU’s designation was further changed in February 1988 to the 15th Marine Expeditionary Unit (MEU); both changes were made to accurately reflect the operational and expeditionary nature of the MAGTF.

Since its activation, the 15th MEU has trained to provide a continuous presence in the Western Pacific, Indian Ocean, Persian Gulf, and as a ready MAGTF for the continental United States.

Below is an overview of operations 15th MEU has supported since its activation, for a detailed history please click here.