to enemy fire. The British specification was more a large, powerful frigate than a ship-of-the-line. The requirement for speed meant a very long vessel, which had to be built from iron. The result was the construction of two s; and . The ships had a successful design, though there were necessarily compromises between 'sea-keeping', strategic range and armor protection. Their weapons were more effective than those of Gloire, and with the largest set of steam engines yet fitted to a ship, they could steam at 14.3 knots (26.5 km/h). Yet the Gloire and her sisters had full iron-armor protection along the waterline and the battery itself. The British Warrior and Black Prince (but also the smaller Defence and Resistance) were obliged to concentrate their armor in a central "citadel" or "armoured box", leaving many main deck guns and the fore and aft sections of the vessel unprotected. The use of iron in the construction of Warrior also came with some drawbacks; iron hulls required more regular and intensive repairs than wooden hulls, and iron was more susceptible to fouling by marine life. By 1862, navies across Europe had adopted ironclads. Britain and France each had sixteen either completed or under construction, though the British vessels were larger. Austria, Italy, Russia, and Spain were also building ironclads. However, the first battles using the new ironclad ships took place during the American Civil War, between Union and Confederate ships in 1862. These were markedly different from the broadside-firing, masted designs of Gloire and Warrior. The clash of the Italian and Austrian fleets at the Battle of Lissa (1866), also had an important influence on the development of ironclad design. First battles between ironclads: the U.S. Civil War The first use of ironclads in combat came in the U.S. Civil War. The U.S. Navy at the time the war broke out had no ironclads, its most powerful ships being six unarmored steam-powered frigates. Since the bulk of the Navy remained loyal to the Union, the Confederacy sought to gain advantage in the naval conflict by acquiring modern armored ships. In May 1861, the Confederate Congress appropriated $2 million dollars for the purchase of ironclads from overseas, and in July and August 1861 the Confederacy started work on construction and converting wooden ships. On 12 October 1861, became the first ironclad to enter combat, when she fought Union warships on the Mississippi during the