Battle of Peleliu

US Marines and then Army troops landed on Peleliu to seize its airfield before the return to the Philippines. Instead of fighting at the beaches, about 11,000 Japanese defenders held hundreds of fortified caves in the Umurbrogol ridges, and an assault expected to take days lasted ten weeks, costing more than 1,500 American and almost all the Japanese lives. Japan's defence in depth was repeated at Iwo Jima and Okinawa.