Officers on deck of Ironclad Monitor - 1862 sepia. Restored and enhanced by Scenesfromthepast.net. USS Monitor was the first ironclad warship commissioned by the United States Navy. She is most famous for her participation in the first-ever naval battle between two ironclad warships, the Battle of Hampton Roads on March 9, 1862, during the American Civil War, in which Monitor fought the ironclad CSS Virginia of the Confederate States Navy. Designed by the Swedish engineer John Ericsson, Monitor was described as a "cheesebox on a raft," consisting of a heavy round revolving iron gun turret on the deck, housing two 11-inch (28 cm) Dahlgren guns, paired side by side. The original design used a system of heavy metal shutters to protect the gun ports while reloading. However, the operation of the shutters proved so cumbersome, the gun crews simply rotated the turret away from potential hostile fire to reload. Further, the momentum of the rotating turret proved to be so great that a system for stopping the turret to fire the guns was implemented on later models of ships in the Monitor class. The crew of Monitor solved the turret momentum problem by firing the guns on the fly while the turret rotated past the target. While this procedure resulted in a substantial loss of accuracy, given the close range at which Monitor operated, the loss of accuracy was not critical. The armoured deck was barely above the waterline. Aside from a small boxy pilothouse, a detachable smokestack and a few fittings, the bulk of the ship was below the waterline to prevent damage from cannon fire. The turret comprised 8 layers of 1-inch (2.5 cm) plate, bolted together, with a ninth plate inside to act as a sound shield. A steam donkey engine turned the turret. The heavily armoured deck extended beyond the waterproof hull, only 5⁄8 inches (15.88 mm) thick. The vulnerable parts of the ship were completely protected. Monitor's hull was built at the Continental Iron Works in the Greenpoint section of Brooklyn, New York, and the ship was launched there on January 30, 1862. Monitor was innovative in construction technique as well as design. Parts were forged in nine foundries and brought together to build the ship; the whole process took less than 120 days. Portions of the heavy iron armour plating for the vessel were made at a forge in Clintonville, New York. In addition to the "cheesebox", its rotating turret, Monitor was also fitted with Ericsson's novel marine screw, whose efficiency and reliability allowed the warship to be one of the first to rely exclusively upon steam propulsion. Ericsson anticipated some aspects of modern submarine design by placing all of Monitor's features except the turret and pilothouse underwater, making it the first semi-submersible ship. In contrast, Virginia was a conventional wooden vessel covered with iron plates and bearing fixed weapons. Although John Ericsson was the designer of the ship itself, Saratoga Springs resident Theodore Timby is credited with the design of the revolving gun turret.After showing his 21-foot (6.4 m) model to officials at the White House, a naval commission recommended Ericsson's ironclad be built with Timby's turret.