page_title: Pre-dreadnought battleship
section_title: Protection
hierarchical_section_title: Pre-dreadnought battleship / Protection
caption_attribution_description: Photo #: NH 76632 USS Kearsarge (BB-5) and USS Kentucky (BB-6) Midship section plan, through the conning tower at Frame 33, showing the ships as designed. The arrangement of armor is depicted, along with one 5/40 broadside gun, an 18-inch above-water torpedo tube, and the steering wheels in both the armored conning tower and the pilothouse. Copied from R. Robinson, Naval Construction, 4th Edition, 1917, page 160-61. U.S. Naval History and Heritage Command Photograph.
context_page_description: Pre-dreadnought battleships were sea-going battleships built between the mid- to late- 1880s and 1905, before the launch of HMS Dreadnought. Pre-dreadnoughts replaced the ironclad battleships of the 1870s and 1880s. Built from steel, protected by hardened steel armour, and powered by coal-fired triple-expansion steam engines, pre-dreadnought battleships carried a main battery of very heavy guns in fully-enclosed rotating turrets supported by one or more secondary batteries of lighter weapons.
  In contrast to the chaotic development of ironclad warships in preceding decades, the 1890s saw navies worldwide start to build battleships to a common design as dozens of ships essentially followed the design of the Royal Navy's Majestic class. The similarity in appearance of battleships in the 1890s was underlined by the increasing number of ships being built. New naval powers such as Germany, Japan, the United States, and to a lesser extent Italy and Austria-Hungary, began to establish themselves with fleets of pre-dreadnoughts. Meanwhile, the United Kingdom, France, and Russia expanded to meet these new threats.
context_section_description: Pre-dreadnought battleships carried a considerable weight of steel armour. Experience showed that rather than giving the ship uniform armour protection, it was best to concentrate armour over critical areas. The central section of the hull, which housed the boilers and engines, was protected by the main belt, which ran from just below the waterline to some distance above it. This "central citadel" was intended to protect the engines from even the most powerful shells. The main armament and the magazines were protected by projections of thick armour from the main belt. The beginning of the pre-dreadnought era was marked by a move from mounting the main armament in open barbettes to an all-enclosed, turret mounting.
  The main belt armour would normally taper to a lesser thickness along the side of the hull towards bow and stern; it might also taper up from the central citadel towards the superstructure. The deck was typically lightly armoured with 2 to 4 inches of steel. This lighter armour was to prevent high-explosive shells from wrecking the superstructure of the ship.
  The battleships of the late 1880s, for instance the Royal Sovereign class, were armoured with iron and steel compound armour. This was soon replaced with more effective case-hardened steel armour made using the Harvey process developed in the United States. First tested in 1891, Harvey armour was commonplace in ships laid down from 1893 to 1895. However, its reign was brief; in 1895, the German Kaiser Friedrich III pioneered the superior Krupp armour. Europe adopted Krupp plate within five years, and only the United States persisted in using Harvey steel into the 20th century. The improving quality of armour plate meant that new ships could have better protection from a thinner and lighter armour belt; 12 inches (305 mm) of compound armour provided the same protection as just 7.5 inches (190 mm) of Harvey or 5.75 inches (133 mm) of Krupp.
caption: Cross-section view amidships of USS Kearsarge, showing how the armour scheme relates to the innards of the ship
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