[3] The site is maintained as Fort Griswold Battlefield State Park by the Connecticut Department of Energy and Environmental Protection.

About 100 feet below the main fort is a battery for additional guns which was built during the Revolutionary War and improved in the late 19th century.

The British were well informed of the layout of Fort Griswold, and Arnold approached the river from such an angle that its guns could not engage his ships.

Arnold's forces split up, some to burn New London and the rest to attack the fort in the Battle of Groton Heights.

It was a sub-post of Fort Trumbull for most of its use by the Army, although it was never actively garrisoned after the Civil War and had an ordnance sergeant as caretaker.