 Long Island Head was centrally situated in Boston Harbor, and the six 10-inch guns of Batteries Hitchcock and Ward (later reduced to five) had an effective range of roughly seven miles, letting them reach Revere on the north, Hingham on the south, and well out to sea in front of the harbor channels.Prior to World War II, the mining casemate at the fort (see map) controlled all the submarine mines that protected the southern approaches to Boston Harbor.The rapid fire 3-inch gun batteries constructed on all three shores of the fort overlooked these minefields to destroy attacking ships that might become entangled in them.