The two 12-inch (305 mm) and five 10-inch (254 mm) guns were the fort's main armament against enemy battleships. For defense against smaller vessels, particularly to defend nearby mine fields against minesweepers, two 4-inch (102 mm) and three 3-inch (76 mm) guns were included. The 4-inch guns were a Navy design by Driggs-Schroeder, and in the whole US Army coast defense system only Fort Warren and Fort Washington in Maryland had this type of gun. Battery Adams was built of low-quality concrete and was disarmed and abandoned due to deterioration in 1914.