A portion of Fort Indiantown Gap occupies the north section of East Hanover Township. In 1932, the Commonwealth of Pennsylvania began to use the area for National Guard training and in 1935 they began to acquire land. The Civilian Conservation Corps constructed buildings, built roads and helped to build Muir Airfield. During WWII, thousands of soldiers trained at the “Gap.” Since then, many training activities for the National Guard, the ROTC and the U. S. Army have occurred there. By 1976, the installation spread over 18,000 acres with 1,635 buildings, 91 miles of road and 64 miles of water lines. It has the largest Army National Guard Aviation facility of its kind, with 80 helicopters from 12 National Guard units.
Indiantown Gap derives its name from the various Native American communities that resided in this region of Pennsylvania. The first inhabitants were Susquehannocks, an Iroquois tribe first encountered by Europeans in the 17th century. In the mid-1700s, Scotch-Irish, English and German pioneers settled the region and managed to live peacefully with the neighboring Lenape Indians. During the French and Indian War, however, tribes who were allied with French colonists raided many English frontier settlements. As Indiantown Gap increasingly became the site of frequent battles, pioneers built a number of defensive structures, including Swatara Fort, Harpers Fort and Reeds Fort.