it to the United States, where it inspired the Second and Third Systems of coastal fortification; the first fully developed example being Castle Williams in New York Harbor which was started in 1807. In the early 19th century, French military engineer Baron Haxo designed a free-standing casemate that could be built on the top of the rampart, to protect guns and gunners from the high-angle fire of mortars and howitzers. The advantages of casemated artillery were proved in the Crimean War of 1853–1856, when attempts by the Royal Navy to subdue the casemated Russian forts at Kronstadt were unsuccessful, while a casemated gun tower at Sevastopol, the Malakoff Tower, could only be captured by a surprise French infantry attack while the garrison was being changed. In the early 1860s, the British, apprehensive about a possible French invasion, fortified the naval dockyards of southern England with curved batteries of large guns in casemates, fitted with laminated iron shields tested to withstand the latest projectiles. However, in the American Civil War (1861-1865), the exposed masonry of casemate batteries was found to be vulnerable to modern rifled artillery; Fort Pulaski was quickly breached in a few hours by only ten of these guns. In contrast, hastily constructed earthworks proved much more resilient. This led to casemates for artillery again falling out of favor. In continental Europe, they were often replaced by rotating gun turrets, but elsewhere large coastal guns were mounted in less expensive concrete gun pits or barbettes, sometimes using disappearing carriages to conceal the gun except at the moment of firing. Casemates for secure barrack accommodation and storage continued to be built; the 1880s French forts of the Séré de Rivières system for example, had a central structure consisting of two stories of casemates, buried under layers of earth, concrete and sand to a depth of , intended to defeat the new high explosive shells. Towards the end of the century, Imperial Germany had developed a new form of fortification called a feste (German article: Festung#Feste), in which the various elements of each fort were more widely dispersed in the landscape. These works, the first of which was Fort de Mutzig near Strasbourg, had separate artillery blocks, infantry positions and underground barracks, all built of reinforced concrete and connected by tunnels or entrenchments. Although the main armament of these forts was still mounted in armored turrets, local defense was provided by