Immediately after the Japanese attack on Pearl Harbor, the Navy reassigned the three battleships to the Pacific Fleet to shore up the fleet's battleship strength. After arriving in California in January 1942, the ships spent the next several months patrolling the west coast of the United States and escorting convoys in the area. They took part in the Aleutian Islands campaign between May and July 1943, with "Idaho" serving as the flagship of the bombardment group that shelled the islands of Attu and Kiska. After maintenance and training at Pearl Harbor, the three "New Mexico"s then took part in the Gilbert and Marshall Islands campaign that began in November, where they provided naval gunfire support to the Marines who stormed ashore at Tarawa, Kwajalein, and Eniwetok, among other islands in the archipelago. These operations continued into January 1944, at which point the fleet began preparations for the next major campaign, which would be directed against the Marianas Islands in the central Pacific.