Before World War I, a large station for handling submarine mines was added to the fort's defenses.

Declared surplus in 1947, the fort served as a Nike missile site until 1961, and was redeveloped in 2005-2009 for a children's summer camp and later a homeless shelter.

In 1893, as part of the Endicott Board's recommendations, construction began at the fort on a series of massive concrete gun batteries to defend the harbor approaches.

A large barracks building for the soldiers and a series of quarters for officers and NCOs were also constructed, as well as structures for mining operations and support functions at the fort.

[6] A quick look at the map will show how Fort Strong's central location made it so well suited for harbor defense.

[9] With a maximum range of 14,000 yards (13,000 m), or almost 8 miles,[10] these guns covered an arc from Revere to North Scituate.

The batteries were intended to engage medium and larger sized ships as directed by the fire control system.

[6] These guns were meant to engage faster moving targets by means of direct fire, and were sited to protect the mine fields that had been laid to block the harbor channels.

In October 1917 the two 4.7-inch guns of Battery Drum were relocated to Sachuest Point in Middletown, Rhode Island.

In 1920-1921 the 3-inch M1898 Driggs-Seabury guns of Battery Basinger were removed and scrapped, part of a withdrawal from service of this type of weapon.

[6] During and for some period after World War II Fort Strong hosted an Army Intelligence Service post.

In 1945-46 German rocket scientist Wernher von Braun and six others were secretly housed at the Army Intelligence Service post at Fort Strong.

[6] The property to the south of the fort was at one time the Long Island State Hospital, and is now operated by the Boston Public Health Commission.