The 3d Marine Division officially activated 16 September 1942 at Camp Elliott, San Diego, California. It was built around the 9th Marines, commanded by Colonel Lemuel C. SHEPHERD, Jr. who later became the 20th Commandant of the Marine Corps. Major General Charles D. BARRETT was the first Commanding General of the Division.

As 1942 drew to a close Headquarters Battalion was still located at Camp Elliott. It busied itself organizing and training for action in the South Pacific. In January and February 1943 the Battalion moved to Auckland, New Zealand.

By August 1943 the Battalion was stationed on Guadalcanal where special training and rehearsals for the Bougainville operation were intensified. On 1 November 1943 the Division landed at Empress Augusta Bay, Bougainville. For approximately two months the Battalion participated in the fight against stiff and heavy enemy resistance. On 16 January 1944, with the transfer of command in the area to the Army?s XIV Corps, the last elements of the Battalion returned to Guadalcanal.

Following the Bougainville operation the Battalion began training for the next campaign. Verbal instructions received in February 1944 led to planning for an operation against the Japanese on Emirau Island. The projected Emirau operation was subsequently cancelled and instructions were received to initiate planning for an operation against enemy forces at Kavieng, New Ireland. This operation was also called off. A few days later the Battalion received word to start training for the amphibious assault against the Japanese on Guam, Marianas.

The Battalion embarked at Guadalcanal on 2 and 3 June 1944 and sailed for Kwajalein, Marshall Islands enroute to the Marianas. It remained afloat off Saipan from 15 to 28 June 1944 as part of the reserve force for the Saipan operation, then being carried out by the 2nd and 4th Marine Divisions in conjunction with the 27th Infantry Division. With the situation on Saipan well controlled the Battalion returned to its restaging area awaiting the target date for the Guam operation.

On 21 July 1944, as a part of the Southern Troops and Landing Force, the Battalion landed on western beaches of Guam in the vicinity of Asan Point. After twenty days of savage fighting the Division troops reaches the northern coast of the island. On 10 August 1944 Guam was declared secure. Until its departure for the Iwo Jima campaign, the Battalion remained on Guam taking part in the mopping up operations.

By the middle of February 1945 the Battalion completed embarkation at Guam preparatory to participation in the Iwo Jima operation. Initially, the Battalion remained afloat off Iwo Jima as Expeditionary Troops Reserve. The Battalion landed on 24 February, and the next morning at the 3d Marine Division launched an attack in its zone between the 4th and 5th Marine Divisions. The 3d Marine Division faced well-organized and determined enemy resistance. The terrain, ideal for defense, was heavily fortified by pillboxes, caves, and covered artillery emplacements. Progress was slow and casualties heavy during the first few days of fighting. The Division slowly pushed the enemy back and by 3 March had severed the last enemy east-west artery of communication by occupying positions overlooking the sea. The 3d Marine Division secured its zone of action on 11 March and then initiated intensive patrolling and mopping-up operations. On 16 March, units of the 3d Marine Division relieved elements of the 5th Division and delivered the final attack of the Iwo Jima operation ? a drive to Kitano Point. Iwo Jima was declared secure on the same day. On 4 April the 3d Marine Division was relieved by Army units.

By mid-April 1945 the Battalion was back on Guam preparing for the next operation. On 3 August 1945 the Battalion received initial plans for the "Olympic" operation which called for an amphibious landing of Kyushu about 1 November 1945. The 3d Marine Division, along with the 2nd and 5th Marine Divisions, was assigned to the V Amphibious Corps for the projected operation. Japan?s agreement to cease hostilities and subsequent surrender cancelled "Olympic", and the Battalion remained on Guam until the date of its disbandment on 28 December 1945. The Battalion was reactivated on 7 January 1952 at Camp Pendleton, California.

Immediately after its activation and still in its organizational state, the Division began intensive combat training, including new tactics and maneuvers based on lessons learned in Korean War. During the remaining part of 1952 elements of the Division participated in numerous exercises and training problems, including vertical envelopment (helicopter landing), air-borne operations and attack, and defense against atomic weapons and missiles.

In August 1953 the Battalion arrived in Japan to support the 1st Marine Division in the defense of the Far Eastern area. In March 1956 the Battalion moved to Okinawa and remained there in a readiness posture until 1965.

On 6 May 1965, the 3d Marine Division opened the Marine Compound at the Danang Air Base, Vietnam. The Battalion operated in Vietnam from this time participating in operations from Danang to Phi Bai to Quang Tri/Dong Ha Combat Base. For Meritorious Service in the Republic of Vietnam during the period 1 January ? 30 September 1968 the Battalion was awarded the Meritorious Unit Commendation. The Battalion departed Vietnam in November 1969 and moved to Camp Courtney, Okinawa, where it is presently located.