The Battle of Tarawa was fought on 20–23 November 1943 between the United States and Japan at the Tarawa Atoll in the Gilbert Islands, and was part of Operation Galvanic, the U.S. invasion of the Gilberts. Nearly 6,400 Japanese, Koreans, and Americans died in the fighting, mostly on and around the small island of Betio, in the extreme southwest of Tarawa Atoll. The Battle of Tarawa was the first American offensive in the critical central Pacific region. It was also the first time in the Pacific War that the United States had faced serious Japanese opposition to an amphibious landing. Previous landings met little or no initial resistance, but on Tarawa the 4,500 Japanese defenders were well-supplied and well-prepared, and they fought almost to the last man, exacting a heavy toll on the United States Marine Corps. The losses on Tarawa were incurred within 76 hours. Background American strategic decisions To set up forward air bases capable of supporting operations across the mid-Pacific, to the Philippines, and into Japan, the U.S. planned to take the Mariana Islands. The Marianas were heavily defended. Naval doctrine of the time held that in order for attacks to succeed, land-based aircraft would be required to weaken the defenses and protect the invasion forces. The nearest islands capable of supporting such an effort were the Marshall Islands. Taking the Marshalls would provide the base needed to launch an offensive on the Marianas, but the Marshalls were cut off from direct communications with Hawaii by a Japanese garrison and air base on the small island of Betio, on the western side of the atoll of Tarawa in the Gilbert Islands. Thus, to eventually launch an invasion of the Marianas, the battle had to start far to the east, at Tarawa. Following the completion of the Guadalcanal campaign, the 2nd Marine Division had been withdrawn to New Zealand for rest and recuperation. Losses were replaced, and the men were given a chance to recover from the malaria and other illnesses that had weakened them through the fighting in the Solomons. On 20 July 1943, the Joint Chiefs directed Admiral Chester W. Nimitz to prepare plans for an offensive operation in the Gilbert Islands. In August, Admiral Raymond A. Spruance was flown to New Zealand to meet with the new commander of the 2nd Marine Division, General Julian C. Smith, and initiate the planning of the invasion with