April 1945: Battle of Okinawa

Okinawa is the largest of the Ryukyu Islands, which are considered the southernmost of the Japanese Home Islands. In preparation for an invasion of the other Home Islands, the Allies invaded Okinawa on 1 April 1945. Fighting on Okinawa was particularly intense, resulting in over 75,000 Allied casualties and over 100,000 Japanese casualties. In addition, half of the civilian population of 300,000 died during the battle; some through crossfire, others as military casualties after being impressed by the Japanese. The Allies managed to seize Okinawa on 2 July 1945.

The high cost in casualties and material, and the refusal of the Japanese to evacuate or shelter the civilian population, convinced the USA that any future invasion of the Home Islands would have a similarly high cost. The Battle of Okinawa was taken as the example for what any invasion of the Home Islands would resemble. This convinced the Allies to delay the invasion of Kyushu until at least November 1945 due to the strength necessary for the operation. It also encouraged alternative strategies to force Japanese surrender, including the use of atomic weapons.