3rd Assault Amphibian Battalion (3rd AABn) is one of two active duty assault amphibian battalions in the United States Marine Corps. The battalion's primary weapon system is the Amphibious Assault Vehicle or AAV. The AAV is a 27.5-ton armored vehicle that carries up to 21 combat-loaded Marines and is armed with the UGWS (UpGunned Weapons Station), which mounts a .50 cal (12.7 mm) M2HB machine gun and a Mk-19 40 mm grenade launcher. The battalion is also equipped with the Amphibious Combat Vehicle or ACV, a rather new variant to the USMC’s amphibious armament which will replace the AAV in years to come. The AAV ACV are the only armored vehicles in the U.S. inventory that are fully capable of operations both on land and in the ocean. The battalion is part of the 1st Marine Division and the I Marine Expeditionary Force. The unit is based in Camp Pendleton, California.
Mission
Land the surface assault element of the landing force and their equipment in a single lift from assault shipping during amphibious operations to inland objectives; to conduct mechanized operations and related combat support in subsequent operations ashore. The specific Mission Essential Tasks List (METL) includes: Preparing combat ready units for deployment and operations in support of the 1st Marine Division Preparing combat ready units for deployment and operations in support of Maritime Pre-Positioned Forces (MPF) to any AOR as directed. Providing sustained amphibious and ground mechanized support to the assault elements of the 1st Marine Division as well as other combat support as directed during subsequent operations ashore. Providing support to the 1st Combat Engineer Battalion and other 1st Marine Division units in the clearing of lanes through minefields and other obstacles during amphibious operations and in support of subsequent operations ashore. Preparing combat ready units for deployment with designated Marine Expeditionary Units (MEU) and deployment to Okinawa as part of the Unit Deployment Program (UDP) in support of 3rd Marine Division
Subordinate units
The 3rd Assault Amphibian Battalion is currently composed of a Headquarters and Service Company, 3 companies located at Camp Pendleton, and three retired companies, one of which being the reinforced company located at the Marine Corps Air Ground Combat Center Twentynine Palms.
History
World War II
3rd Assault Amphibian Battalion was originally activated 16 September 1942 at San Diego, California, as 3rd Amphibian Tractor (Amtrac) Battalion and assigned to the 3rd Marine Division. During December 1942 the battalion relocated from San Diego a short distance up the coast to Camp Pendleton. After training for a few months the battalion then deployed in February–March 1943 to Auckland, New Zealand in preparation for combat in the Pacific theater.
During World War II, the battalion was primarily armed with Landing Vehicle Tracked (LVT), specifically the LVT-2 also known as "WATER BUFFALOS".
The battalion fought in the following combat actions:
Bougainville with 124 LVT-1s
Guam with 193 LVT-2s and LVT-4s
Iwo Jima with 90 LVT-2s
For its actions in World War II, 3rd Amphibian Tractor Battalion was awarded the Presidential Unit Citation Streamer, Asiatic-Pacific Campaign Medal Streamer With Four Bronze Stars, and the World War II Victory Medal Streamer.
At the conclusion of World War II the battalion redeployed in March 1945 to Maui, territory of Hawaii and then relocated during February 1946 back to Camp Pendleton, California. It was deactivated several months later on 1 May 1946.
1952 - 1966
3rd Amphibian Tractor Battalion was reactivated 1 April 1952 at Camp Pendleton, California, and assigned to Fleet Marine Force, Pacific. It was subsequently reassigned during October 1955 to the 1st Marine Division. Elements participated in the Cuban Missile Crisis, October–December 1962
During this period the battalion was still armed with LVTs - transitioning primarily to the LVT-5 in the late 1950s.
Vietnam War and 1970s
3rd Amphibian Tractor Battalion deployed during February 1965 to Camp Schwab, Okinawa and redeployed again in June 1965 to the Republic of Vietnam. There the battalion fought in the Vietnam War from June 1966 - January 1970. During this conflict the battalion distinguished itself at: Chu Lai Da Nang An Hoa Hoi An
Throughout Vietnam the battalion was armed with variants of the LVT-5.