Code-named Operation Iceberg - This battle was fought over the Ryukyu Islands and included the largest amphibious assault in the Pacific Theater of WW2. The reason for this attack was to get a large island close the the Japanese mainland, so that they can launch air attacks against the mainland and possibly invade - this was code-named Operation Downfall.
This battle was called "Typhoon of Steel" in English and "Rain of Steel" in Japanese. This was because one of the tactics used by the Japanese was kamikaze attacks, which was the major reason that the Japanese lost so many people in this battle. Source 19, Wikimedia Commons - Map of the battle of Okinawa Map
http://commons.wikimedia.org/wiki/File:Battle_of_Okinawa.svg |
Source 18, Wikipedia - Two Marines from the 2nd Battalion, 1st Marines advance on Wana Ridge on 18 May 1945
https://en.wikipedia.org/wiki/Battle_of_Okinawa#/media/File:Ww2_158.jpg |