Montana-class Battleships US Navy - World War II

Displacement: 66,040 tonsLength: 920 ft., 6 in.Beam:  121 ft.Draft:  36 ft., 1 in.Propulsion:  8 Ãâ€" Babcock Wilcox 2-drum express type boilers, 4 Ãâ€" Westinghouse geared steam turbines,  4 Ãâ€" 43,000  hp Turbo-electric transmission  turning 4 propellersSpeed:  28 knots Armament (Planned) 12 Ãâ€" 16-inch (406  mm)/50 cal Mark 7 guns (4  Ãƒâ€" 3)20 Ãâ€" 5-inch (127  mm)/54 cal Mark 16 guns10–40 Ãâ€" Bofors 40 mm anti-aircraft guns56 Ãâ€" Oerlikon 20 mm anti-aircraft cannons Background Recognizing the role that a naval arms race had played in the run-up to World War I, leaders from several key nations gathered in November 1921 to discuss preventing a recurrence in the postwar years.  These conversations produced the Washington Naval Treaty in February 1922 which placed limits on both ship tonnage and the overall size of the signatories fleets.  As a result of this and subsequent agreements, the US Navy halted battleship construction for over a decade after the completion of the Colorado-class USS West Virginia (BB-48) in December 1923.  In the mid-1930s, with the treaty system unraveling, work began on the design of the new North Carolina-class.  With global tensions rising, Representative Carl Vinson,  Chairman of the House Naval Affairs Committee, pushed forward the Naval Act of 1938 which mandated a 20% increase in the US Navys strength.   Dubbed the Second Vinson Act, the bill allowed for the construction of four South Dakota-class battleships (South Dakota, Indiana, Massachusetts, and Alabama) as well as the first two ships of the Iowa-class (Iowa and New Jersey).  In 1940, with World War II underway in Europe, four additional battleships numbered BB-63 to BB-66 were authorized.  The second pair, BB-65 and BB-66 were initially slated to be the first ships of the new Montana-class.  This new design represented the US Navys response to Japans Yamato-class of super battleships which commenced construction in 1937.  With the passage of the Two-Ocean Navy Act in July 1940, a total of five Montana-class ships were authorized along with an additional two Iowas.  As a result, hull numbers BB-65 and BB-66 were assigned to the Iowa-class ships USS Illinois and USS Kentucky while the Montanas were renumbered BB-67 to BB-71.  Ã‚  Ã‚   Design Concerned about rumors that the Yamato-class would mount 18 guns, work on the Montana-class design commenced in 1938 with specifications for a battleship of 45,000 tons.  Following early assessments by the Battleship Design Advisory Board, naval architects initially increased the new class displacement to 56,000 tons.  Additionally, the board requested that the new design be 25% stronger offensively and defensively than any existing battleship in the fleet and that it was permissible to exceed the beam restrictions imposed by the Panama Canal to obtain the desired results.  To obtain the additional firepower, designers armed the Montana-class with twelve 16 guns mounted in four three-gun turrets.  This was to be supplemented by a secondary battery of twenty 5/54 cal. guns placed in ten twin turrets.  Designed specifically for the new battleships, this type of 5 gun was intended to replace the existing 5/38 cal. weapons then in use. For protection, the Montana-class possessed a side belt of 16.1 while the armor on the barbettes was 21.3.  The employment of enhanced armor meant that the Montanas would be the only American battleships capable of being protected against the heaviest shells used by its own guns.  In this case, that was the super-heavy 2,700  lb. APC (armor-piercing capped) shells fired by the 16/50 cal. Mark 7 gun.  The increase in armament and armor came at a price as naval architects were required to reduce the class top speed from 33 to 28 knots to accommodate the extra weight.  This meant that the Montana-class would not be able to serve as escorts for the fast Essex-class aircraft carriers or sail in concert with the three preceding classes of American battleships.   Fate The Montana-class design continued to undergo refinements through 1941 and was finally approved in April 1942 with the goal of having the ships operational in the third quarter of 1945.  Despite this, construction was delayed as the shipyards capable of building the vessels were engaged in constructing Iowa- and Essex-class ships.  After the Battle of the Coral Sea the following month, the first battle fought solely by aircraft carriers, the building of the Montana-class was indefinitely suspended as it became increasing clear that battleships would be of secondary importance in the Pacific.  In the wake of the decisive Battle of Midway, the entire Montana-class was canceled in July 1942.  As a result, the Iowa-class battleships were the last battleships to be built by the United States. Intended Ships Yards USS Montana (BB-67): Philadelphia Naval ShipyardUSS Ohio (BB-68): Philadelphia Naval ShipyardUSS Maine (BB-69): New York Naval ShipyardUSS New Hampshire (BB-70): New York Naval ShipyardUSS Louisiana (BB-71): Norfolk Naval Shipyard The cancellation of USS Montana (BB-67) represented the second time a battleship named for the 41st state had been eliminated.  The first was a South Dakota-class (1920) battleship that was dropped due to the Washington Naval Treaty.  As a result, Montana became the only state (of the 48 then in the Union) never to have had a battleship named in its honor. Selected Sources Military Factory: Montana-class BattleshipsGlobal Security: Montana-class Battleships