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".
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 Reactivated several months later on 1 May 1946.
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.
