A torpedo cruiser is a type of warship that is armed primarily with torpedoes. The major navies began building torpedo cruisers shortly after the invention of the locomotive Whitehead torpedo in the 1860s. The development of the torpedo gave rise to the Jeune École doctrine, which held that small warships armed with torpedoes could effectively and cheaply defeat much larger battleships. Torpedo cruisers fell out of favor in most of the great power navies in the 1890s, though many other navies continued to acquire them into the early 1900s. The Imperial Japanese Navy rebuilt two light cruisers into torpedo cruisers during World War II. Unlike the earlier vessels, these ships were intended to launch their Long Lance oxygen torpedoes at extreme range at night to surprise enemy warships. They never saw action in their intended role, however, and were quickly converted into troop transports. History The torpedo cruiser emerged from the Jeune École, a strategic naval concept that argued that the large ironclad battleships then being built in Europe could be easily—and more importantly, cheaply—defeated by small torpedo-armed warships. In newly unified Germany, the new torpedo cruiser was embraced as a powerful weapon for a new navy which had no real blue-water traditions of shipbuilding or seafaring. Early German torpedo vessels were classified as avisos, the first being , launched in 1876. She was initially armed with just two torpedo tubes, supplemented in 1878 by two guns and six machine guns. The enthusiasm of the German Kaiserliche Admiralität (Imperial Admiralty) was particularly marked during the tenure of General Leo von Caprivi: a total of eight vessels were built, designed to serve with flotillas of smaller torpedo boats, and integrated into a defensive system of minefields and coastal artillery. The typical German torpedokreuzer came to be armed with a salvo of three torpedo tubes, one fixed in the bows and two on rotating mounts on either side of the hull. Their gun armament was relatively modest, with two medium-calibre weapons mounted fore and aft, and a number of smaller broadside guns in sponsons, designed primarily to defend against smaller attackers such as torpedo boats. Concurrently with the German procurement of Zieten, the Italian Regia Marina laid down the small cruiser in 1875, which was armed with a single torpedo tube and two machine guns. The Regia Marina built a further seventeen torpedo cruisers over five classes over the course of the