The Empire of Japan invaded Morotai early in 1942 as part of its Dutch East Indies Campaign. US forces and their allies launched the Battle of Morotai in 1944; bombing the island in August and invading it in September. Imperial Japanese forces on Morotai held out until 1945 but failed to expel the Allied troops. In the latter part of 1944, 61,000 personnel landed on Morotai. Two thirds of them were engineers, who rapidly established facilities including harbors and two airstrips plus extensive fuel stores.