In 1917, the prison camp was used again to temporarily house sailors from the , the first German prisoners-of-war taken by the United States in World War I. Five years later, in 1922, Asan Point was converted into a United States Marine Corps camp. However, the camp, and much of the rest of Guam, was demilitarized in 1931 as a result of U.S. isolationism between the World Wars. During the Japanese occupation from 1941, Japanese forces constructed defensive strongpoints at Asan and Adelup Points, as well as the Libugon highlands overlooking Asan Bay. In 1944, the U.S. military chose the Asan Invasion Beach as the northern attack beginning the Battle of Guam. Three battleships, three cruisers, and three destroyers, as well as carrier-based aircraft, bombarded the area, destroying all pre-war structures in Asan. The bombardment was followed by 180 landing craft bringing Marines to the shore in the face of fierce Japanese resistance.
