Marshall Islands campaign

Marshall Islands campaign. This group of 36 Micronesian Pacific atolls includes Kwajalein, the world's largest. During the Pacific war they formed part of the outer defensive perimeter guarding Japan, to which they had been mandated after the First World War.

A US marine and army amphibious force of 85,000 combat, garrison, and construction personnel, carried and escorted by an armada of nearly 300 warships and landing craft, invaded the group on 30 January 1944. Reconnaissance troops landed on Majuro Atoll, the first US occupation of Japanese soil, before 4th Marine and 7th Infantry Divisions landed on the inner islands of Kwajalein Atoll, Kwajalein, and the twin islets of Roi-Namur, ULTRA intelligence having revealed that the Japanese had moved men to the outer atolls in the expectation of landings there. After being neutralized by air attacks, these outer atolls were bypassed and did not surrender until the end of the war, but after Eniwetok Atoll had been occupied, US forces completely controlled the area.

Despite confusion during some of the landings, the lessons learned at Tarawa the previous November resulted in a brilliantly executed campaign which proved of immense strategic value. It forced the Japanese fleet to withdraw from Truk and brought forward the invasion date of the Mariana Islands by 20 weeks.