By the summer of 1944, U.S. military power in the Pacific Theater had grown spectacularly. Beginning nine days after the D-Day invasion in France, American forces launched their largest attacks yet against the Japanese-held islands of Saipan on June 15, Guam on July 21, and Tinian on July 24. Situated 1,200 to 1,500 miles south of Japan, the crescent-shaped archipelago known as the Marianas was strategically important to the defense of the Empire, protecting vital shipping lanes from Asia and a widened aerial attack of the homeland.
Over the next sixty days, each of the three islands fell to the Americans. During grueling land and sea campaigns, U.S. forces killed 60,000 Japanese soldiers, sailors, and airmen, while the Japanese inflicted just under 30,000 total casualties on the Americans, killing 5,500.