page_title: Armored cruiser
section_title: Armored cruisers in the pre-dreadnought era
hierarchical_section_title: Armored cruiser / History / Armored cruisers in the pre-dreadnought era
caption_attribution_description: English: USS South Dakota.
context_page_description: The armored cruiser was a type of warship of the late 19th and early 20th centuries. It was designed like other types of cruisers to operate as a long-range, independent warship, capable of defeating any ship apart from a battleship and fast enough to outrun any battleship it encountered. Varying in size, it was distinguished from other types of cruiser by its belt armor—thick iron plating on much of the hull to protect the ship from shellfire much like that on battleships. The first armored cruiser, the Imperial Russian Navy's General-Admiral, was launched in 1873 and combined sail and steam propulsion. By the 1890s cruisers had abandoned sail and took on a modern appearance.
  For many decades naval technology had not advanced far enough for designers to produce a cruiser which combined an armored belt with the long range and high speed required to fulfill its mission; for this reason, many navies preferred to build protected cruisers in the 1880s and early 1890s.
context_section_description: The development of rapid–fire cannons in the late 1880s forced a change in cruiser design. Since a large number of hits at or near the waterline could negate the effect of water–excluding material used in protected cruisers, side armor again became a priority. Four inches (c. 10 cm) was considered adequate. However, it had to cover not just guns and the waterline but also much of the hull structure in–between; otherwise, the equally new high–explosive shells could penetrate and destroy much of the unarmored portion of the ship. Another development was the publication in 1890 of American naval strategist Alfred Thayer Mahan's book The Influence of Sea Power upon History. While Mahan emphasized the importance of battleships above all other types of warships in obtaining command of the sea, armored cruisers and large protected cruisers could still be used as second-class battleships to maintain control of the sea lanes and potentially as fighting units of a battle fleet.
  The armored cruisers built in the mid– to late–1890s were often as large and expensive as pre-dreadnought battleships. They combined long range, high speed and an armament approaching that of battleship with enough armor to protect them against quick-firing guns, considered the most important weapons afloat at the time. Their speed was made possible due to another development, case-hardened steel armor—first Harvey armor and then crucially Krupp armor. The higher tensile strength of these armors compared to nickel steel and mild steel made it feasible to put a light yet useful armor belt on a large cruiser. They saved further weight by not requiring a heavy timber backing, as previous armor plating had, to soften and spread the force of the impact from oncoming shells; 2.5 inches (64 mm) of teak to give a fair surface upon which to attach them was all that was needed. Moreover, this belt could also be much wider than previously, covering the center of the hull, where the ammunition and engines were located, from the main deck to five feet below the waterline. Steel bulkheads added strength to the hull, while armor as thick as the belt covered the guns and heavier protection surrounded the conning tower. With these improvements, the ships became more fully protected than was possible previously. They were also expensive to maintain at fighting strength as they required a greater number of stokers to feed the boilers than a battleship when steaming at flank speed.
  The ideas presented by Mahan prompted French Admiral Ernest François Fournier to write his book La flotte necessaire in 1896. Fournier argued that a fleet of technologically advanced armored cruisers and torpedo craft would be powerful and flexible enough to engage in a wide range of activity and overwhelm potential enemies. French naval and government circles embraced this ideal mutually and even advocates of battleships over cruisers admitted the latter's potential usefulness in scouting and commercial warfare. The result was the building of increasingly large armored cruisers. Jeanne d'Arc, laid down in 1896, displaced 11,000 tons, carried a mixed armament of 194-millimetre (7.6 in) and 138-millimetre (5.4 in) guns, and had a 150-millimetre (5.9 in) belt of Harvey armor over her machinery spaces. The 12,300-ton Léon Gambetta class and 14,000-ton Edgar Quinet class followed. With a speed of 22.5 knots, the Léon Gambettas were armed with four 194-millimetre (7.6 in) guns in twin turrets and 16 164-millimetre (6.5 in) in four single and six twin turrets and were protected by up to 150-millimetre (5.9 in) of Krupp belt armor and nearly 200-millimetre (7.9 in) on their conning towers and turrets. The Edgar Quinets, slightly faster at 23 knots, were armed with 14 194-millimetre (7.6 in) guns and carried up to 170-millimetre (6.7 in) of armor on their belts, almost 100-millimetre (3.9 in) on their decks and 150-millimetre (5.9 in) on their turrets.
  Britain, which had concluded as early as 1892 that it needed twice as many cruisers as any potential enemy to adequately protect its empire's sea lanes, resp
caption: USS South Dakota, one of the Pennsylvania class
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