It was one of the last places prior to invading the main islands of Japan. They Japanese defense was strong and took a lot of effort and men to overcome it. If the US had to invade the main islands, there would have been tens of thousands of casualties. ========= The battle for Okinawa was different from other battles with Japan in that there was a significant civilian population on Okinawa. There were reports of many civilians committing suicide in the midst of the battle. American forces 'believed Okinawa was a foretaste of an invasion of Japan' due to the prescence of civilian populations and didn't want to percipitate civilian suicides. Atomic bombs unfortunateky had the same effect but at least the war was bought to a much faster end and overall much fewer deaths on both sides. Estimates are that many hundreds of thousands of lives were saved by bringing the war to a faster end.