Silent film showing the start of the Battle of Okinawa, codenamed Operation Iceberg, fought on the Ryukyu Islands of Okinawa. This was the largest amphibious assault in the Pacific War of World War II. The 82-day-long battle lasted from early April until mid-June 1945. After a long campaign of island hopping, the Allies were approaching Japan, and planned to use Okinawa, a large island only 340 mi (550 km) away from mainland Japan, as a base for air operations on the planned invasion of Japanese mainland (coded Operation Downfall). Four divisions of the U.S. 10th Army (the 7th, 27th, 77th, and 96th) and two Marine Divisions (the 1st and 6th) fought on the island. Their invasion was supported by naval, amphibious, and tactical air forces.

The battle has been referred to as the “typhoon of steel” in English, and tetsu no ame (“rain of steel”) or tetsu no bōfū (“violent wind of steel”) in Japanese. The nicknames refer to the ferocity of the fighting, the intensity of kamikaze attacks from the Japanese defenders, and to the sheer numbers of Allied ships and armored vehicles that assaulted the island. The battle resulted in the highest number of casualties in the Pacific Theater during World War II. Based on Okinawan government sources, mainland Japan lost 77,166 soldiers, who were either killed or committed suicide, and the Allies suffered 14,009 deaths (with an estimated total of more than 65,000 casualties of all kinds). Simultaneously, 42,000–150,000 local civilians were killed or committed suicide, a significant proportion of the local population. The atomic bombings of Hiroshima and Nagasaki together with the Soviet invasion of Manchuria caused Japan to surrender less than two months after the end of the fighting in Okinawa.