Battery Hunter, a World War II casemate, was built to house two 6-inch guns. The bunker, 15 acres of surrounding land, and 500 feet of beach around it were occupied by the Navy from 1950 until 1981. From 1950 to 1957, it served as headquarters for the Navy Harbor Defense Unit's anti-submarine listening system that protected the mouth of Delaware Bay. In 1962, it became Naval Radio Station Lewes, supporting the National Emergency Command Post Afloat system for use in case of nuclear war. In 1964, the radio station moved to nearby Fort Miles Battery 519. In 1965, Battery Hunter reverted to the Naval Reserve as a training facility for Inshore Undersea Warfare Division 401, later Mobile Inshore Undersea Warfare Unit 604. In 1981, when the Navy's secret Sound Surveillance System facility at Cape Henlopen's Herring Point closed, Battery Hunter was also turned over to Delaware State Parks. The year 2015 marked the 100th anniversary of the Navy Reserves that operated on this site from 1957 to 1981.