1st Marine Division

United States Army General Douglas MacArthur planned to prevent attacks in his rear area during the reconquest of the Philippines by taking the Morotais and the Palaus. The most heavily defended island in the Palaus was Peleliu. He felt that he need to hold Peleliu before he could move on the Philippines.

In July 1942, the combatants in the Pacific were in a stalemate. The Japanese advance had been slowed at Midway, but they held a temporary numerical and tactical advantage. Admiral Chester W. Nimitz knew that he could not sustain an advance for at least another year.