USS North Carolina (BB-55) is the lead ship of the North Carolina class of fast battleships, the first vessel of the type built for the United States Navy. Built under the Washington Treaty system, North Carolina design was limited in displacement and armament, though the United States used a clause in the Second London Naval Treaty to increase the main battery from the original armament of twelve 14-inch (356 mm) guns in quadruple turrets to nine 16 in (406 mm) guns in triple turrets. The ship was laid down in 1937 and completed in April 1941, while the United States was still neutral during World War II.