north that a massive 10-in Parrott would finally break the previously impenetrable walls of the fort, which had become the symbol of stalwart steadfastness for the Confederacy. The Washington Republican described the technical accomplishments of the 10-in Parrott: The 3-3/4" bore 24-pound shot, with a muzzle velocity of 1,625 feet per second, strikes a target at 3,500 yards with a velocity of about 300 feet per second (this is almost beyond the range of the weapon). In contrast, the 10" bore 300-pound shot, with a muzzle velocity of 1,111 feet per second, strikes the target at the same range still moving at 700 feet per second, due to its much higher mass to drag ratio. The resulting huge difference in impact energy, 33,000 ft-lb for the 24 lb, and over 2,000,000 ft-lb for the 300 lb, means the penetrating energy of the larger shell is 20 times that of the smaller. In terms of the ability to punch holes in fortifications, at that long range the light 24 lb shell would be expected to only breech a 6" thick brick wall. In contrast, the greater mass and retained velocity of the 300 lb shell would enable it to penetrate 6 to 7 feet of brick (given the quality of the material back then). The Union soldiers knew Fort Sumter's brick walls averaged about 5 feet thick, and thus recognized the potential for such a cannon to help them succeed in taking back their Fort. Swamp Angel A famous large Parrott cannon, called the Swamp Angel, was used by federal Brigadier General Quincy Adams Gillmore to bombard Charleston, South Carolina. It was manned by the 11th Maine Volunteer Infantry Regiment. On August 21, 1863 Gillmore sent Confederate general P. G. T. Beauregard an ultimatum to abandon heavily fortified positions at Morris Island or the city of Charleston would be shelled. When the positions were not evacuated within a few hours, Gillmore ordered the Parrott rifle to fire on the city. Between August 22 and August 23, the Swamp Angel fired on the city 36 times (the gun burst on the 36th round), using many incendiary shells which caused little damage and few casualties. The battle was made more famous by Herman Melville's poem "The Swamp Angel". After the war, a damaged Parrott rifle said to be the Swamp Angel was moved to Trenton, New Jersey, where it rests as a memorial