The United States Navy's carrier aviation program began in 1922 when USS Langley (CV-1) — converted from the collier Jupiter — became the fleet's first aircraft carrier. Though slow and limited in capacity, Langley gave Navy aviators and planners the experience needed to develop the tactics, deck procedures, and operational concepts that would define carrier warfare. Two years later, the Washington Naval Treaty redirected two partially completed battlecruiser hulls into the fleet carriers USS Lexington (CV-2) and USS Saratoga (CV-3), each capable of embarking over 70 aircraft. These ships dominated fleet exercises through the 1930s and proved the potential of massed carrier air power before the first shot of World War II was fired.
By the late 1930s, purpose-built fleet carriers entered service: USS Yorktown (CV-5), USS Enterprise (CV-6), USS Wasp (CV-7), and USS Hornet (CV-8). When Japanese aircraft struck Pearl Harbor on December 7, 1941, the Pacific Fleet's carriers were at sea and escaped destruction. Over the next twelve months those few ships — often fighting alone — bore the entire weight of the Pacific war. At the Battle of Midway in June 1942, carrier aircraft sank four Japanese fleet carriers in a single day, turning the tide of the war in the Pacific.
Mass production of the Essex class, authorized beginning in 1940, gave the Navy the fast-carrier striking force that drove across the Central and Western Pacific. Paired with the light carriers of the Independence class, these ships formed the most powerful naval aviation force the world had ever seen, delivering the air superiority that made the island-hopping campaign possible from the Gilberts to the Japanese home islands.