Fort Indiantown Gap derived its name from the American Indian village known as Indiantown and the gap in the Blue Mountain where Indiantown was located. Indian artifacts found in the Lebanon and Swatara Valleys indicate an aboriginal presence as early as 2,500 BC.
Established in 1931, Fort Indiantown Gap was built as a National Guard training center. During World War II, it was used as a training site for seven Army divisions, and also as a demobilization site once the war was over. Fort Indiantown Gap later trained large numbers of soldiers and officers during the wars in Korea, Vietnam, and the Persian Gulf War.
Memorial Lake was established in 1945 in memory and honor of Pennsylvania National Guard soldiers who served in World War I and World War II.
In 1955, Memorial Lake was transferred to the Department of Forest and Waters, now the Department of Conservation and Natural Resources, and became Memorial Lake State Park. It continues to provide recreational opportunities for military personnel as well as civilians.