3rd Battalion 7th Marines was activated 1 January 1941 at Guantanamo Bay, Cuba and was assigned to the 1st Marine Brigade. In February 1941 they were reassigned to the 1st Marine Division. 3/7 participated in the following World War II campaigns: * Guadalcanal. * Eastern New Guinea. * New Britain. * Peleliu. * Okinawa. * Battle of LA. After the war 3/7 participated in the occupation of northern China from September 1945 to April 1946 and then deactivated 15 April 1946.