해전
Naval warfare was transformed by many innovations, most notably the coal-based steam engine, highly accurate long-range naval guns, heavy steel armour for battleships, mines, and the introduction of the torpedo, followed by the torpedo boat and the destroyer. Coal after 1900 was eventually displaced by more efficient oil, but meanwhile navies with an international scope had to depend on a network of coaling stations to refuel. The British Empire provided them in abundance, as did the French Empire to a lesser extent. War colleges developed, as military theory became a specialty; cadets and senior commanders were taught the theories of Jomini, Clausewitz and Mahan, and engaged in tabletop war games. Around 1900, entirely new innovations such as submarines and airplanes appeared, and were quickly adapted to warfare by 1914. The British HMS "Dreadnought" (1906) incorporated so much of the latest technology in weapons, propulsion and armour that it at a stroke made all other battleships obsolescent.