Picture over 1,400 ships gathered on the ocean. That is what the waters around Okinawa looked like on April 1, 1945. It was the largest amphibious attack in the Pacific during World War II. Okinawa is a long, narrow island south of mainland Japan. American military leaders chose it for a reason. They needed a place close enough to Japan to launch planes for future missions. Taking Okinawa would give them airfields and harbors they badly needed. The fighting lasted almost three months. Japanese forces hid in caves and tunnels dug into the hills, making the battle long and difficult. More than 12,000 American soldiers lost their lives. The cost on the Japanese side was far greater, with over 100,000 soldiers killed. What made the battle even more tragic was the suffering of Okinawa's own people. Around 100,000 Okinawan civilians died during the fighting. They were caught between two massive armies on their small island. When the battle ended on June 22, American forces controlled the island. But the enormous casualties on both sides changed how leaders thought about the war. Some historians believe the losses at Okinawa changed President Truman's thinking. The fighting had been so costly that he chose to use the atomic bomb instead of invading Japan.