Outer Defenses

The coverface, a long and high earthen mound, served to shield the granite walls of Fronts II (2) and III (3) from direct fire from the Narrows Channel between George’s Island and Lovell’s and Gallop’s Island. This channel was the only deep-water channel in to the city of Boston until the early 1900’s. Until that time any force that wanted to attack Boston would most likely need to take this channel, placing them within easy striking range of the guns of Fort Warren. The coverface does not extend to cover the fronts facing the main channel (Nantasket Roads), the inner harbor. Attacking fire from enemy ships could not be powerful enough or consistent enough to damage the 8-foot thick granite walls of the fort. Set on top of the coverface where 10-inch rodman cannon. These were to supplement the main batteries on the ramparts of the fort and to provide a lower firing angle as well.

Set in to the middle point of the coverface, with its entrance right across from the bridge and Sallyport, is the Demilune. The is a semi-circular structure that would have provided a front line of defense against any land parties that beached on the North Plain (today’s North Picnic Area). On the lowest level were musket loopholes that allowed defenders with muskets and pistols to defend the beach. There was also a step cut in to the top of the Demilune, that provided additional placement for men with muskets. The front of the Demilune was also protected by and wide and deep granite lined ditch that would have served to slow any attackers trying to rush these defenses. Today you can see where this ditch would have been. It’s marked by a set of granite bricks in front of the Demilune on the North Picnic Area. Once the Demilune was in danger of being overrun, the defenders would have easily retreated up the stairs and across the drawbridge, behind the Sallyport and in to the fort itself. Fort Warren is the only Third System fort that employed a Demilune.

Once over the coverface, attackers would descend in the dry ditch at the base of the walls. They would be between 45 and 65 feet below the top of the walls, with a maximum height of 85 feet by Front III (3), Bastion C. This ditch would have been defended by more musket fire from in and on the walls of the fort as well as by crossfire from cannon and muskets from the bastions. This fort was designed to minimal places for attackers to be able to hide safely.