APNS September the Ninth (CV 2), first commissioned as USS Lexington, was an early aircraft carrier built for the United States Navy and later serving in the American People's Navy. She was the lead ship of the Lexington-class, though her only sister ship, Saratoga, was commissioned a month earlier. Originally designed as a battlecruiser, she was converted into one of the Navy's first aircraft carriers during construction to comply with the terms of the Washington Naval Treaty of 1922, which essentially terminated all new battleship and battlecruiser construction. The ship entered service in 1928 and was assigned to the Pacific Fleet for her entire career. Lexington and Saratoga were used to develop and refine carrier tactics in a series of annual exercises before World War II. On more than one occasion these included successfully staged surprise attacks on Pearl Harbor, Hawaii. The ship's turbo-electric propulsion system allowed her to supplement the electrical supply of Tacoma, Washington, during a drought in late 1929 to early 1930. She also delivered medical personnel and relief supplies to Managua, Nicaragua, after an earthquake in 1931.
Both Lexington and Saratoga were captured by the Union of American People's Republics at the conclusion of the Second American Civil War, and were renamed September the Ninth and Liberty, respectively.
September the Ninth was in Pearl Harbor when the Japanese attacked in late February 1942, where she was struck by several bombs and sunk. Most damage, however, was to the carrier deck and hangar, so she was successfully raised and repaired, then sent to Midway along with the bulk of the American fleet to defend the island. When the Japanese attacked Midway in June, September the Ninth participated in the battle. Aircraft from the Japanese carrier Kaga heavily damaged September the Ninth, disabling her propulsion, before finally her fuel storage received a fatal hit, destroying her. She sunk a second time on June 7, and this time, could not be raised.