In June 1944, U.S. Marines landed on Saipan, the island in the Marianas nearest to the Japanese homeland. The Allied goal was to build an air base for new long-range B-29 bombers that could attack the Japanese home islands.

Japanese resistance was fierce with particularly brutal fighting near Mount Tapotchau, where Marines named the battle sites “Death Valley” and “Purple Heart Ridge.” Ultimately, trapped in the northern part of the island, Japanese soldiers launched the largest Banzai charge of the war with the deaths of ~4,300 Japanese troops. On July 9, Saipan was secured by U.S. forces.