Upper Level - Front 2 Terreplein

The terreplein is the main, cannon bearing level of a fortification or defensive work. The terreplein of Fort Warren supported 10-inch smoothbore Rodman Cannon along the fronts with 15-inch smoothbore Rodman Cannon at each bastion corner. Cannon are generally named for the size of the shot or shell they fired. A 10-inch cannon would fire a shot or shell 10-inches in diameter. Whereas a 32-pound cannon fired a 32-pound shot or shell. By 1867, 188 cannons where mounted at Fort Warren. The Rodman Cannon was named for Thomas Jackson Rodman, who developed the technique for manufacturing cannon that allowed for much larger guns to be made. The largest gun produced using this technique as a 20-inch, though only two were made and those were experimental just to prove they could be done. The 10-inch cannon were mounted on stone arches that had an iron plate on top. This allowed the guns to be traversed side to side to converge fire on a target. The 15-inch guns were mounted on stone pedestals with two circular iron plates on top. These guns were able to traverse 360 degrees allowing them to both defend against attacking ships but also in close quarters defense of the fort interior. By the end of the Civil War smoothbore cannon were rendered obsolete by advances in rifling. Some of the 10-inch guns at Fort Warren were fitted with an insert sleeve that updated the guns allowed them to fire more modern 8-inch rifled projectiles.