The Japanese Yamato had the largest and most powerful main guns, firing 18.1-inch (460 mm) shells. The American Iowa class was armed with 16-inch (406 mm) guns, which were larger than the German Bismarck's 15-inch (38 cm) guns. The Yamato's guns had the greatest destructive potential due to their enormous size, while the Iowa's guns offered the advantages of accuracy and speed, and the Bismarck's guns were the least powerful of the three, though the ship itself was a formidable pre-war design. Y