During the Japanese occupation of Guam, it was not as heavily fortified as the other Mariana Islands such as Saipan that had been Japanese possessions since the end of World War I. But by 1944, Guam had a large Japanese garrison.
Det var inte så tungt befäst som de andra öarna i Marianerna som Saipan som hade varit en japansk besittning sedan slutet av första världskriget, men som 1944 hade en stor japansk garnison.