The Battleship USS Iowa

There are not many warships in the history of world shipbuilding with so many superlatives which describe their specification. The American battleship Iowa (BB-61), prototype of a four ship class commissioned for the US Navy during World War II is probably the leading contender, as far as superlatives are concerned.
The most powerful battleship built in the USA, the longest and fastest battleship in history,  in commission for the longest of the four sisters, and so on and so forth… and she is still in existence today.

1. Genesis

It would have seemed that naval operations of the major naval powers during  World War I clearly demonstrated the twilight of the battleship era, but that was not going to be the case while these extremely costly war machines still decided the strength of each major naval power. It was no wonder that the danger of the naval arms race had not vanished when Great Britain, the United States, Japan and Italy emerged victorious from the Great War.
The major powers, exhausted by the war, were not inclined to spend huge amounts of money on building new dreadnoughts when their economies were on the verge of collapse. Nevertheless each one embarked on a program of battleship design and construction based on the perceived lessons of the late war, perhaps because it was a way of maintaining a skilled workforce, and reducing the enormous number of unemployed as a result of demobilisation .
Eventually economics forced on the great powers the idea of an international agreement, which in its essence was to stop the frantic arms race or at least limit its scope. The Washington Naval Treaty, signed on February 6, 1922 by the representatives of major naval powers limited the construction of new battleships for a few years. The number of existing battleships was also reduced with numerous useless and obsolete vessels being scrapped.
However new ideas and new designs were emerging, in particular in Germany and Japan, but France and Italy were also active. The result of this activity was the treaty signed by major naval powers at the London Naval Conference in 1930  to extend the period of “building holidays”, since it prohibited the construction of new battleships until 1935. The Second London Naval Disarmament Conference, opened in December 1935, ended in a fiasco. Japan’s representatives withdrew from the agreement since they thought it was unfair, which de facto marked the beginning of a new naval arms race and the end of “building holidays”.

Iowa 2

During the aforementioned “holiday” period none of the great powers  ceased the study of new battleships, nor did Germany. Despite the fact that in Britain and the USA the design work was in strict compliance with treaty limits as far as armament and displacement was concerned, numerous designs were created, which served as the basis for construction of the first battleships of a new generation. Following the Congressional appropriation on June 3, 1936, the construction of two new battleships was launched in the United States. The North Carolina and Washington set new standards for American battleships.  Initially, they were to be armed with reliable 356 mm (14”) guns, but finally the new 406 mm (16”) guns were approved, because American intelligence had been informed that Japan was building a warship with specifications far exceeding limits posed by the treaty.
The North Carolina class battleships were ultimately armed with nine 406 mm (16”) guns mounted in three triple turrets. However, there was no time to modify the design and increase the armour thickness of the ships which were already being built. Thus, these two well armed warships were considered inadequately armoured. Although the General Board of the US Navy was going to request Congressional appropriation for two more battleships of the North Carolina class in the fiscal year 1938, it encountered a strong opposition of the Chief of Naval Operations, Admiral William D. Leahy, who demanded warships which would be both better designed and armoured.
Therefore, the preliminary design work on a new battleship for the fiscal year 1939 began in March 1937. Meeting the “treaty” displacement limit set at 35 000 standard tons for the new ship was still the main assumption. At that displacement the ships were to have the same armament as the North Carolina, but increased armour protection. It was quite a challenge for the Bureau of Construction and Repair.
Within such limits, it was clear that the new ships had to have shorter hulls, so with the increased armour thickness in comparison to that of the North Carolina, the length of the armoured citadel of the “all or nothing”1 system, commonly used since the construction of the battleship Nevada, had to be shorter. Its reduced length allowing for the increase in armour thickness. Another challenge was to maintain the required speed of 27 knots, which with shorter hull and thicker armour required the installation of a more powerful machinery set than that of the North Carolina, in a smaller space in the shorter hull.