For Japan, it was a nearly continuous series of losses, beginning with the Battle of the Philippine Sea near the Mariana Islands on June 19–20, 1944. In this huge sea battle, Japan lost most of its naval air power. Three Japanese aircraft carriers were sunk and more than 300 airplanes destroyed. The ground battles in these campaigns were similar in character to those on Guadalcanal and New Guinea: the fighting involved guerilla-style warfare with very high casualty counts, especially for the Japanese. For example, in the Battle of Leyte, which took place in the Philippines between October 20 and December 31, 1944, the Japanese lost 49,000 soldiers out of a total of 55,000 involved in the conflict. In the same conflict, the United States lost only 3,500 troops.
One by one, the Allies liberated Japanese-controlled islands until the last obstacle between Allied forces and the Japanese mainland were the Ryukyu Islands, which included Okinawa. However, each battle was more intense and more costly than the previous one, which led military commanders to begin rethinking their strategy.
A small island off the Japanese coast, Iwo Jima served as an early warning station against Allied bombers en route to attack Japan. As the Allies closed in on Japan, Iwo Jima became an obvious target. Following a heavy bombardment of the island by aircraft and battleships, U.S. Marines began an amphibious assault on February 19, 1945. Over 20,000 Japanese troops were garrisoned on Iwo Jima, and the entire island was honeycombed with underground tunnels and bunkers, especially Mt. Suribachi, which overlooked the southern end of the island.
After U.S. forces came ashore, they surrounded the base of Mt. Suribachi within a single day. Ascending the mountain was another matter entirely, as the Japanese fought from their hidden tunnels and small bunkers on the steep, ash-covered slopes. After a brutal, four-day struggle, U.S. forces reached the peak of Mt. Suribachi on February 23, where an Associated Press photographer took a now world-famous photograph of a group of Marines raising the American flag. Although taking the mountain was a victory in itself, it would be more than a month before U.S. forces secured the entire island. Approximately 20,000 Japanese soldiers—nearly all the forces on the island—were killed. The American death toll was 7,000.
The Battle of Okinawa was the last large-scale battle in the Pacific and the most intense of the island invasions. Unlike Iwo Jima, Okinawa had a large civilian population, which became one of the great tragedies of the battle.
U.S. forces began amphibious landings on April 1, 1945. Japan had more than 100,000 soldiers lying in wait in a series of fortified defensive lines. The Japanese believed that the Allied weakness would be its large fleet of naval vessels anchored offshore. As a result, they planned a massive series of kamikaze attacks on these ships—suicide missions in which Japanese pilots crashed their fuel- and bomb-laden planes into targets—with the goal of destroying the ships or forcing them to abandon their troops on land. However, these kamikaze attacks did not do nearly as much damage as the Japanese had anticipated, and the U.S. fleet was able to remain in place and continue to offer air support to the troops on the ground.