Operation Iceberg was the codename of which major WWII battle?

The Battle of Okinawa, codenamed Operation Iceberg, was a series of battles fought in the Japanese Ryukyu Islands, centered on the main island of Okinawa. It began with the largest amphibious assault in the Pacific War on 1 April 1945. The Allied forces were faced against an estimated 155,000 ground, air and naval troops on an immense island that was home to an estimated 500,000 civilians. Operation Iceberg was to be vast in comparison to any other Allied operation in the Pacific under naval command. Which is probably the reason the name ,Operation Iceberg, was used considering the actual islands were small but the troop count and number of civilians present proposed a large problem lurking beneath. The battle lasted 82 days ending on 22 June 1945. It was one of the bloodiest battles in the Pacific, resulting in over 100,000 Japanese causalities and 50,000 Allied causalities.

The Battle of Normandy was codenamed Operation Overlord. The Battle of the Bulge was codenamed by the Germans, Unternehmen Wacht am Rhein (Operation Watch on the Rhein). The Battle of Midway was codenamed by the Japanese, Operation MI.