Iwo Jima and Okinawa

In 1945 US forces attacked islands close to Japan, encountering defenses that showed how costly an invasion of Japan itself might be. Iwo Jima, a volcanic island needed as a base for fighters and emergency landings of B-29 bombers, was invaded on 19 February. Its roughly 21,000 Japanese defenders fought from tunnels and caves, and almost all died; about 6,800 Americans were killed. Joe Rosenthal's photograph of Marines raising the flag on Mount Suribachi became an icon. On 1 April US forces landed on Okinawa, part of Japan's own territory.

The battle lasted nearly three months, with massive kamikaze attacks on the fleet. About 12,500 Americans and roughly 100,000 Japanese soldiers, including Okinawan conscripts, died, and estimates of Okinawan civilian deaths range from about 40,000 to 150,000, with some coerced by the Japanese military into mass suicide. US planners used these battles to estimate casualties for an invasion of Japan.