Carriers act as floating airfields, carrying fighters and bombers far from friendly territory to be launched against enemy targets. This allows an air strike against targets on both land and sea that would otherwise be far out of range. Catapults flush with the flight deck assist in launching aircraft; for landing, aircraft are fitted with retractable hooks that engage transverse wires on the deck, braking them to a quick stop. Aircraft landings are guided by radio and radar and by visual signals from the deck.
During World War I The British navy developed the first true carrier with an unobstructed flight deck, the HMS Argus, built on a converted merchant-ship hull. The first U.S. carrier, a converted collier renamed the USS Langley, joined the fleet in March 1922.
Carriers were first used in combat during the early stages of World War II. The Japanese attack on Pearl Harbor by carrier-based planes on Dec. 7, 1941, dramatically demonstrated the potential of the aircraft carrier, which thereafter was the dominant combat vessel of the war. The range of the aircraft launched from carriers forever changed the methodology of naval battles. Opposing fleets could now engage in battle without either fleet ever entering the other's visual range, ending the dominance of the battleship as the strongest vessel on the sea. 