The first aircraft carriers made their appearance in the early years of World War I. These first flattops were improvised affairs built on hulls that had been laid down with other purposes in mind, and it was not until the 1920s that the first purpose-built carriers were launched, but no-one was as yet clear about the role of the carriers and they were largely unloved by the 'battleship admirals' who still believed that their great dreadnoughts were the ultimate capital ships.
World War II changed all that, At Taranto, Pearl Harbor, and in the North Atlantic, the carrier, the ugly duckling of the world's navies, proved itself to be the dreadnought nemesis. As the tide of war turned, the fast attack carriers of the U.S. Navy spearheaded the counter-attack in the Pacific while the makeshift escort carriers helped to seal the fate of the German U-boats in the Atlantic. The carrier, and naval aviation, thus emerged into the post-war world as the primary symbol and instrument of sea power; it would play a crucial role in the strategic encirclement of the Soviet Union and enabled western airpower to be rapidly and effectively deployed in areas of conflict as remote as Korea, Vietnam, the Falklands and the Gulf.