A Marine Expeditionary Unit (MEU) is a self-contained, rapid-response force of approximately 2,200 Marines and sailors that deploys aboard a three-ship Amphibious Ready Group (ARG). Each MEU includes a ground combat element (infantry battalion), an aviation combat element (composite squadron with helicopters, tiltrotors, and attack aircraft), and a logistics combat element capable of sustaining operations for 15 days without resupply. MEUs are designated Special Operations Capable (SOC) after completing a rigorous pre-deployment training cycle and are designed to be the nation's force-in-readiness — capable of launching within 6 hours of notification for missions ranging from humanitarian aid to embassy evacuation to amphibious assault. All information in this article is derived from publicly available U.S. Department of Defense sources and official Marine Corps fact sheets.

The U.S. Marine Corps maintains seven MEUs — three based on the West Coast, three on the East Coast, and one forward-deployed in Japan — ensuring at least two are deployed or ready to deploy at any given time. The 11th Marine Expeditionary Unit is one of three West Coast MEUs headquartered at Marine Corps Base Camp Pendleton, California, falling under I Marine Expeditionary Force. It typically rotates through the Western Pacific, Indian Ocean, and Middle East, operating within the U.S. 5th and 7th Fleet areas of responsibility. The 11th MEU has participated in operations including Iraqi Freedom, Enduring Freedom, and humanitarian assistance missions across Southeast Asia and the Horn of Africa. All information in this article is derived from publicly available U.S. Marine Corps fact sheets and official Department of Defense publications.

The 13th Marine Expeditionary Unit is the second of three West Coast MEUs based at Camp Pendleton under I Marine Expeditionary Force. It shares the same rotational deployment cycle as the 11th and 15th MEUs, typically deploying to the Western Pacific, Persian Gulf, and Indian Ocean. The 13th MEU has a notable operational history including participation in Operation Restore Hope in Somalia, operations in Afghanistan, and multiple deployments supporting maritime security in the Strait of Hormuz and surrounding waterways. Like all MEUs, its specific subordinate battalion and squadron assignments rotate with each deployment cycle. All information in this article is derived from publicly available U.S. Marine Corps fact sheets and official Department of Defense publications.

The 15th Marine Expeditionary Unit rounds out the West Coast MEU triad at Camp Pendleton under I Marine Expeditionary Force. It gained widespread recognition for being among the first conventional ground forces into Afghanistan in November 2001 during Operation Enduring Freedom, conducting a dramatic long-range helicopter assault to seize Forward Operating Base Rhino south of Kandahar. The 15th MEU has since deployed repeatedly to the Middle East and Western Pacific, supporting operations ranging from combat missions to tsunami relief in the Indian Ocean. Its rotational cycle ensures that as one Camp Pendleton MEU deploys, another is in training workup, and a third is in post-deployment reset. All information in this article is derived from publicly available U.S. Marine Corps fact sheets and official Department of Defense publications.