Early in 1945 the Allies began closing in on Japan.  American bombers began more frequent and daring raids by flying in low during the night to be more accurate.  During these raids the bombers began dropping incendiary (fire-producing) bombs.  Many Japanese cities were set on fire with this bomb and in March of 1945 after a very aggressive bombing raid the heart of Tokyo was destroyed.  In order to continue to destroy Japan the Allied leaders decided they needed more air bases so they could increase their bombing raids.  The Japanese islands of Iwo Jima and Okinawa were chosen.  On February 19, 1945 American Marines landed on Iwo Jima.  At Iwo Jima there were close to 20,000 Marine casualties, the were the heaviest suffered during any island invasion.  Japanese forces hung on till March 16, 1945.  Okinawa was the next island to be invaded.  Allied troops started to pour ashore on April 1, 1945.  Kamikaze pilots were sent to attack the forces.  By the time Okinawa was finally captured and the battle ended on June 21, 1945 the kamikaze pilots sank more then 30 ships and damaged at least 350 others.
    The United States, Britain, and China threatened to destroy Japan unless they surrendered.  Japanese leaders paid no attention to the threat, they just kept on fighting.
    Finally the United States unleashed a very powerful weapon that would devastate Japan and force them to surrender.