battalion relocated to New River, North Carolina during April 1941. World War II 1st Battalion, 11th Marines was reassigned during March 1942 to the 3rd Marine Brigade. It was deployed during March 1942 to Western Samoa. The battalion was again reassigned to the 1st Marine Division in September 1942. The battalion participated in the Guadalcanal and New Britain campaigns; it also carried out operations on Finschhafen, Peleliu and Okinawa. After the war the battalion was redeployed in September 1945 to Tientsin, China. It participated in the occupation of North China from September 1945 to January 1947. It was then redeployed during January 1947 to Guam, and detached from the 1st Marine Division. While in Guam, the unit constructed Camp Witek, the 1st Marine Brigade base. The battalion was reassigned during June 1947 to the 1st Marine Brigade. It was deactivated on 1 October 1947. Korean War The battalion was reactivated on 1 October 1949 at Camp Pendleton and assigned to the 1st Marine Division. It was then reassigned during July 1950 to the 1st Provisional Marine Brigade. The battalion was then deployed in July and August 1950 to Pusan in Korea. The battalion participated in the Korean War, from August 1950 to July 1953, taking part in the actions at the Battle of the Pusan Perimeter, at Inchon and the Chosin Reservoir. Personnel also saw action on the East-Central and Western Fronts. 1st Battalion, 11th Marines participated in the occupation of the Korean Demilitarized Zone from August 1953 to March 1955. It returned to Camp Pendleton in April 1955. Vietnam War The battalion deployed during August 1965 to Camp Hansen, Okinawa and redeployed during January 1966 to Chu Lai, in the Republic of Vietnam. It was reassigned to the 3rd Marine Division. During March 1966, the unit was reassigned to the 1st Marine Division. The battalion operated from Chu Lai, Da Nang, Quang Tri, Phu Bai, Con Thien, Ca Lu, Khe Sanh, Cua Viet, Dong Ha and Quang Nam from January 1966 to March 1971. It was reassigned during 1971 to the 3rd Marine Amphibious Brigade; it returned during March 1971 to Camp Pendleton and reassigned to the 1st Marine Division. Alpha Battery 1st Battalion 11th Marines was known as Alpha North in early 1966. On the night of 18 April 1966 Alpha North was overrun. It suffered 5 marines killed and 28 wounded. All of the howitzers received damage.