The United States Navy grew rapidly during World War II from 1941–45, and played a central role in the war against Japan. It also assisted the British Royal Navy in the naval war against Germany and Italy. The U.S. Navy grew slowly in the years prior to World War II, due in part to international limitations on naval operations in the 1920s. Battleship production restarted in 1937, commencing with the USS North Carolina (BB-55). The navy was able to add to its fleets during the early years of the war while the US was still neutral, increasing production of vessels both large and small, deploying a navy of nearly 350 major combatant ships by December 1941 and having an equal number under construction.