Key Point: All of the late American battleship designs combined a grim practicality with a streamlined aesthetic. Because of their length and narrow lines, the Iowas were the pinnacle of the effort.
The North Carolina– and South Dakota–class battleships were designed with the limits of the Washington Naval Treaty in mind. Although much more could be accomplished in 1938 with thirty-five thousand tons than in 1921, sacrifices still had to be made. As had been practice in the first round of battleship construction, U.S. Navy architects accepted a low speed in return for heavy armor and armament. Consequently, both the South Dakotas and the North Carolinas had speeds a knot or two slower than most foreign contemporaries. The Montanas, the final battleship design authorized by the Navy, would also have had a twenty-eight-knot maximum speed. In any case, Japan’s failure to ratify the 1936 London Naval Treaty bumped the maximum standard tonnage from thirty-five to forty-five thousand, giving the designers some extra space to work with. The result was the Iowa class, the most powerful and best-designed battleships ever built.
USS Missouri, the third laid down but last completed of the Iowa class, carried a slightly heavier main armament than the South Dakotas and could make five extra knots. The Iowas were the first U.S. Navy battleships to make speed a primary value, and achieved the speed through a longer hull and more powerful machinery. Indeed, the Iowas are the fastest battleships ever built, outpacing even the Italian Littorios by a knot or two. While no Iowa ever recorded a speed higher than thirty-one knots, rumors over the years suggested that the battleships might be able to make thirty-five knots over short distances. Part of the rationale for building the Iowas was to have ships capable of chasing down and destroying the Japanese Kongo-class battlecruisers, themselves built in 1913, but the Navy also wanted to ensure that it had battleships capable of keeping up with the Essex-class carriers.