High Quality Content by WIKIPEDIA articles! The United States Navy began building a series of battlecruisers in the 1920s, more than a decade after their slower and less heavily armed armored cruisers had been rendered obsolete by the Royal Navy`s Invincible-class battlecruisers. Construction of these ships was abandoned under the terms of an armaments limitation treaty, though two were completed as aircraft carriers. The US Navy subsequently ordered six "large cruisers"—which are often considered battlecruisers by historians—in 1940, of which only two entered service.