for the ship was completed in 1844 and called for a ship in beam and displacing 1,500 tons. She was to be armed with six large-caliber muzzle-loading cannons in open casemates on decks, loaded from below the main deck by gun crews protected by armored casemates employing sloped armor to further improve protection. She was to be proof against 64-pound (29-kilogram) shells, the largest fired by U.S. Navy guns at the time. To achieve this, she was to be armored with thick iron plate reinforced by of locust timber, a thickness of iron and wood believed by the Stevens to be sufficient to resist any gun then known. Furthermore, she was to be semisubmersible, able to submerge herself to her gunwales to make her a smaller target for enemy gunners. Her steam engines were to produce 900 indicated horsepower (ihp) and give her an estimated top speed of r), and this very high speed for the era combined with good maneuverability were intended to make her a hard target to hit as well. Experiments by John Ericsson with his 12-inch (305-mm) wrought iron gun Oregon, which could fire a 225-pound (102-kilogram) shell , soon proved that 4.5-inch (114-millimeter) armor was insufficient. In March 1845, Robert Stevens' health failed and he spent the next two years recuperating in Europe. His absence and the need to rethink the ship's armor scheme led to little work being done on her for several years. In 1851, Secretary of the Navy George Bancroft ordered work on the ship stopped because of her inadequate armor, and Commodore Charles W. Skinner, chief of the Navy's Bureau of Construction announced his intention to scrap the incomplete ship and sell her materials. The 1854 design The Stevens brothers succeeded in getting Congress to overrule Bancroft and Skinner, and set about radically redesigning the Stevens Battery. The new design was ready by January 1854. It called for a great increase in the ship's size and capabilities. She was now to be long, in beam, and displace 4,683 tons. She was to be proof against 125-pound (56.7-kilogram) shells, with armor made up of 6.75-inch (171-millimeter) iron plates sloping upwards from below the waterline to the main deck and running along the entire side of the ship from stem to stern. She was to have bulwarks to make her more seaworthy when steaming which could be lowered to reduce her freeboard in