Actually to destroy or capture shore batteries by naval force is another matter. As Ericsson said, "A single shot will sink a ship, while 100 rounds cannot silence a fort."[1] Attacks of this kind against Fort McAllister and Charleston failed. At Charleston, April 7, 1863, the ironclads faced a cross-fire from several forts, 47 smoothbores and 17 rifles against 29 smoothbores and 4 rifles in the ships, and in waters full of obstructions and mines. [Footnote 1: Wilson, IRONCLADS IN ACTION, Vol. I, p. 91.] The capture of Fort Fisher, commanding the main entrance to Wilmington, North Carolina, was accomplished in January, 1865, by the combined efforts of the army and navy. The fort, situated on a narrow neck of land between the Cape Fear River and the sea, had 20 guns on its land face and 24 on its sea face, 15 of them rifled. Against it were brought 5 ironclads with 18 guns, backed up by over 200 guns in the rest of the fleet. After a storm of shot and shell for three successive days, rising at times to "drum-fire," the barrage was lifted at a signal and troops and sailors dashed forward from their positions on shore. Even after this preparation the capture cost 1000 men. As at Kinhurn in the Crimean War, the effectiveness of the naval forces was due less to protective armor than to volume of fire. _Submarines and Torpedoes_ In the defense of Southern harbors, mines and torpedoes for the first time came into general use, and the submarine scored its first victim. Experiments with these devices had been going on for centuries, but were first brought close to practical success by David Bushnell, a Connecticut Yankee of the American Revolution. His tiny submarine, resembling a mud-turtle standing on its tail, embodied many features of modern underwater boats, including a primitive conning tower, screw propulsion (by foot power), a vertical screw to drive the craft down, and a detachable magazine with 150 pounds of gunpowder. The _Turtle_ paddled around and even under British men-of-war off New York and New London, but could not drive a spike through their copper bottoms to attach its mine.