The most famous naval battle of the war was the duel at Hampton Roads between the Union turreted ironclad and the Confederate casemate ironclad (built from the scuttled remains of ). "Casemate ship" was an alternative term for "central battery ship" (UK) or "center battery ship" (US). The casemate (or central battery) was an armored box that extended the full width of the ship protecting many guns. The armored sides of the box were the sides of hull of the ship. There was an armored bulkhead at the front and rear of the casemate, and a thick deck protecting the top. The lower edge of the casemate sat on top of ship's belt armour. Some ships, such as (laid down 1873), had a two-story casemate. A "casemate" was an armored room in the side of a warship, from which a gun would fire. A typical casemate held a 6-inch gun, and had a front plate (forming part of the side of the ship), with thinner armor plates on the sides and rear, with a protected top and floor, and weighed about 20 tons (not including the gun and mounting). Casemates were similar in size to turrets; ships carrying them had them in pairs, one on each side of the ship. The first battleships to carry them were the British laid down in 1889. They were adopted as a result of live-firing trials against in 1888. Casemates were adopted because it was thought that the fixed armor plate at the front would provide better protection than a turret, and because a turret mounting would require external power and could therefore be put out of action if power were lost – unlike a casemate gun, which could be worked by hand. The use of casemates enabled the 6-inch guns to be dispersed, so that a single hit would not knock out all of them. Casemates were also used in protected and armored cruisers, starting with the 1889 . and retrofitted to the 1888 during construction. In the pre-dreadnought generation of warships, casemates were placed initially on the main deck, and later on the upper deck as well. Casemates on the main deck were very close to the waterline. In the Edgar-class cruisers, the guns in the casemates were only above the waterline. Casemates that were too close to the waterline or too close to the bow (such as in the 1912 Iron