USS Yorktown, the first of the class
With the launch of the Japanese Kongou Class battlecruisers the year prior, in 1913 the US Navy began work on designing a new battlecruiser to counter the Japanese. The US Navy's previous class of battlecruiser, the Constellation Class being woefully under armed compared to both the Kongous and the British Lion class. The original design called for a similar armament to both the Kongous and Lions, eight 356mm guns in four twin turrets. However due to congressional budget constraints and the fact that all 356mm guns were being used for the New York class and the then the under construction Nevada class battleships, and the time needed to manufacture new guns would take too long.
It was decided instead to a modified version of the triple turrets on the Nevada class to carry the older 305mm gun used in the previous battleships and the Constellation Class. After about two years of construction, the first of the class, USS Yorktown, was launched, and then commissioned into the fleet in early 1916. At her launch she was both the most heavily armed warship in the world and the fastest, featuring a massive 15 gun main battery and a 30 knot top speed. Her main belt was a 203mm, a standard for most battlecruisers of the time. Her sistership, USS Cowpens was commissioned into the fleet later in 1916.
Despite an impressive main battery and high speed, the gun caliber of the ships was inadequate for most capital ships by 1916. The two ships would join up with the rest of the US fleet sent over to Scapa Flow following US entry into the Great War. At the end of the war and subsequent Washington Naval Treaty the US was allowed to keep the two battlecruisers in exchange for either scrapping or selling the Wyoming class battleships. Both would subsequently be sold to both Spain and Qing dynasty China. Wyoming going to Spain being renamed as San Pedro, and Arkansas being renamed Dong Wei in Chinese service.
The two Yorktowns would be modernized in the interwar years, receiving new fire control systems and eventually a more intensive rework in where her boilers would be replaced with more modern powerplants, boosting her speed to 32 knots, and her superstructure expanded upon. The two ships would survive the Pearl Harbor attack, being out with the carriers at the time of the attack. The two ships would serve as escorts for the carriers throughout the Pacific campaign, receiving a heavy anti-air upgrades through out. USS Cowpens would be heavily damaged by a Kamikaze off the coast of Okinawa in 1945. She would make it back to Pearl for repairs but would miss out the rest of the war. At the end of the war the two ships would be used in the Operation Crossroads test in 1946.