The Lexington-class battlecruisers were officially the only class of battlecruiser to ever be ordered by the United States Navy.[A 1] While these six vessels were requested in 1911 as a reaction to Japan's Kongō class, the envisioned use for the Lexingtons in the U.S. Navy came from a series of studies by the Naval War College. These stretched over several years and predated the existence of the first battlecruiser, HMS Invincible; a series of proposed battlecruiser designs was submitted to the General Board in 1909 but was not approved for construction.
The Lexingtons were instead later included as part of the Naval Act of 1916. Like the South Dakota-class battleships, also included in the act, their construction was repeatedly postponed in favor of escort ships and anti-submarine vessels, required by the US Navy during WWI. During these delays, the Lexingtons were redesigned several times; they were originally designed to mount ten 14-inch guns and eighteen five-inch guns on a hull with a maximum speed of 35 knots (65 km/h; 40 mph), but by the time of the definitive design, these specifications had been altered to eight 16-inch guns and sixteen six-inch guns, with a speed of 33.25 knots (61.58 km/h; 38.26 mph) to improve hitting power and armor (the decrease in speed was mostly attributed to the additions of armor).
The design challenges the Navy's Bureau of Construction and Repair (C&R) faced with this class were considerable, as the combined requirements of optimum hitting power, extreme speed and adequate protection taxed the knowledge of its naval architects and technology of the time. The desired speed of 35 knots, for example, had been previously attained only in destroyers and smaller craft. To do so with a capital ship required a hull and a power plant of unprecedented size for a U.S. naval vessel, in addition to careful planning by its designers to ensure it would have enough longitudinal strength to withstand both bending forces while underway and any stress that might occur in combat. It took years between initial and final designs for engine and boiler technology to provide a plant of sufficient power that was also compact enough to allow a practical degree of protection, even in such large ships.
While four of the ships were eventually canceled and scrapped on their building ways in 1922 to comply with the Washington Naval Treaty, two (Lexington and Saratoga) were converted into the United States' first fleet carriers.[A 2] Both saw extensive action in World War II, with Lexington conducting a number of raids before being sunk during the Battle of Coral Sea and Saratoga serving in multiple campaigns in the Pacific and the Indian Ocean. Though she was hit by torpedoes on two different occasions, Saratoga survived the war only to be sunk as a target ship during Operation Crossroads