How were the people of Guam liberated?

On July 21, 1944, the U.S. launched the largest and most complex amphibious assault in the Pacific Theater up until that date, Operation Detachment, to retake the island of Guam. Rear Admiral Richard L. Conolly led a force of 50,000 servicemen, including the U.S. 3rd Marine Division. This time, U.S. forces knew that the Japanese would be prepared for an attack, and took steps to avoid the disasters that had occurred in the previous campaign.

To counter Japanese defenses centered around Mount Santa Rosa and the Fonte Plateau, General Holland Smith devised a scheme to cut the island in two. While the 1st Provisional Marine Brigade and the U.S. 77th Infantry Division feigned a landing at Tumon Bay, the main invasion force (3rd Marine Division) landed at Agat Bay. The ruse drew off Japanese reserves and allowed the Marines to land unopposed on July 21, 1944. The main force advanced swiftly; bypassing bypassed the Fonte Plateau and trapped Japanese forces there and on Mount Santa Rosa. These Japanese defenders were effectively isolated from the rest of the island. While the Marines cut the island in half on July 24, the remaining defenders fought a bitter engagement against units from the 77th Infantry Division for control of the Apra Harbor naval base. Apra Harbor was secured by July 30.

The isolated Japanese forces in the south surrendered on August 10. However, a pocket of fierce resistance held out in the north for two more months. Elements of the 3rd Marine Division mopped up the remaining Japanese until the island was finally declared secure on December 10. During this time, 10,000–15,000 CHamorros were forcibly taken to concentration camps by Japanese forces, where they were starved and tortured. The Guamanians held out for some 32 months under the most grueling conditions imaginable, until U.S. forces liberated the Pacific islands in 1944.

The battle lasted nearly three weeks, and approximately 1,800 U.S. servicemen were killed while another 5,500 were injured. Japanese casualties were estimated to be between 18,000 and 20,000 while approximately 1,000 CHamorros were killed during the battle.