The coastal artillery base defended the Atlantic coast and the entrance to New York Harbor, with its first gun batteries operational in 1896.

The Sandy Hook Light, built in 1764 and the oldest working lighthouse in the United States, is located on the grounds of Fort Hancock.

[4] Following the Civil War, it was determined that masonry forts were vulnerable to rifled guns, and funding for their construction was cut off in 1867.

[3] These resulted from the large-scale Endicott Program, which in 1885 proposed a new, comprehensive system of forts defending port cities.

[7] The Endicott Program centered on disappearing guns, which would remain concealed behind a concrete-and-earth parapet until raised to fire.

11, the first operational gun of the Endicott Program) and was completed in 1894, but for some reason was not accepted for service until 1898, possibly due to extensive testing.

This was designed to place the mortars as closely together as possible, in the hope of scoring multiple hits on an enemy ship by firing simultaneously in a bracketing "shotgun" pattern.

The pits were separated by a traverse, which were the ammunition magazines and storages areas that ran the width and breadth of the Battery.

The entire battery was surrounded by a high concrete wall covered with earth for land defense.

They were begun as the seven-gun Battery Halleck in 1896, built on top of the third system fort, and were divided in 1904 after expansion to nine guns.

[13] The 3-inch (76 mm) batteries were often called "mine defense" guns, intended to defend a minefield against minesweepers.

On 9 May 1942 Fort Hancock became part of the Harbor Defenses of New York and the Sandy Hook command was disestablished.

[18][19] Following the American entry into World War I a number of changes took place at forts in the US, with a view to getting US-manned heavy and railway artillery into service on the Western Front.

[5] Also, four mortars (one from each pit) of Battery Reynolds-McCook were removed in 1917 to be remounted at the Highlands Military Reservation to the south of Sandy Hook.

[5] Following World War I a number of additional changes took place in the Coast Artillery, and Fort Hancock was no exception.

The 3-inch (76 mm) M1898 guns of Battery Urmston were removed in 1920 as one of several weapon types withdrawn from service at this time.

[20][21] In 1940–41 Fort Hancock served as a mobilization center, with first a tent city and subsequently numerous temporary buildings accommodating trainees.

A museum is managed as part of the Sandy Hook Unit of Gateway National Recreation Area.

In 2013, the Park Service introduced Nubian goats to the fort in order to clear away poison ivy that has been growing unchecked on the six-acre property for about 40 years.

[23] The 21st Century Federal Advisory Committee was formed in September, 2012, intended for citizens to advise the National Park Service on potential redevelopment of the Fort's unused buildings.

Since then, various rehabilitation and adaptive re-use proposals have been solicited for lease of the various buildings from the National Park Service.

The Launch Area was heavily damaged in Hurricane Sandy, but the radar site, located at Horseshoe Cove, is under restoration by US Army Air Defense Artillery veterans of the Cold War era, several of whom were stationed at Fort Hancock in the 1960s-70s.