The Pacific Endgame, the Atomic Bomb, and the War's Human Cost

American forces landed on Iwo Jima in February 1945, facing a Japanese defensive system of tunnels and bunkers whose defenders resisted almost to the last man, and then on Okinawa in April 1945, beginning what became the longest and bloodiest land battle of the entire Pacific war. Japanese forces launched massive kamikaze attacks against the Allied fleet off Okinawa, including the mission that sank the battleship Yamato, and the staggering casualties of these battles weighed heavily on American planning for a projected invasion of the Japanese home islands, Operation Downfall, whose catastrophic casualty estimates later featured prominently in the decision to use the atomic bomb.