The fort first served as a
coast artillery installation and ended its service as a
Nike Hercules and
Nike Ajax missile site. However, the historic gun batteries and other military fortifications remain closed to the public. Some of these structures are very hazardous. The mortars were taken from Battery Piper at
Fort Hamilton in Brooklyn, and the six-inch guns were brought in from Battery Burke at Fort Hamilton and Battery Kinney at
Fort Slocum on Davids' Island. In 1918–1919 a battery of two
3-inch antiaircraft guns was installed at the fort. The facility became part of the
Harbor Defenses of Southern New York, joining Fort Hamilton and
Fort Wadsworth on Staten Island. The railway mortars and their tracks were probably removed in 1921 to make room for Battery Harris. The battery was named for Henry Leavenworth Harris, a career Army officer who died in 1920. After the war it was determined that gun defenses were obsolete, and Fort Tilden was disarmed, with all guns removed for scrap in 1948. In 1955, the AA guns were replaced by a
Nike–Ajax missile site called NY–49. A photograph shows at least two launch sites with six rails each were at Fort Tilden. == Nature area ==