The Japanese Navy had a tradition of producing innovative battleship designs which were the equal, or better, of many of their foreign contemporaries. When Nagato was commisioned in 1920, she was probably the most powerful battlewagon then afloat, with her very powerful 16-inch armament, good protection, and very respectable speed. Yamato's commisioning in 1941 re-established Japan as the nation with the world's most powerful battleship, as she completely outclassed any ship then afloat. Only with the arrival of the U.S. Iowa-class would this title be seriously challenged. Japan's older capital ships, too, had been extensively modernized during the interwar period, and all of them (with the possible exception of Fuso and Yamashiro, due to their age and low speeds) were capable of being used in the front lines of a modern naval war. The maturation of naval aviaition, of course, drastically reduced their utility in actual practice, so that Japan's battleships (even mighty Yamato) did what most other nations' did in World War II: escorted aircraft carriers and provided additional anti-aircraft screening for them.