The earliest class of U.S. battleships to see service in the Pacific War was the Wyoming class.

    These two ships, Wyoming and Arkansas, were constructed in the wake of the 1908 Newport Conference, and sizably larger ships than their predecessor classes, Utah and South Carolina.

    Although the Newport Conference had moved the power of designating ship characteristics from the Board on Construction to the General Board, the Wyoming class was still largely a BoC design.

    The reason for desiring a whole new design was partly due to a strong believe that future battleships of prospective opponents would mount larger guns than the standard 12” artillery of most current battleships.

    However, even the apparently modest increase from 305mm to 356mm, or from 12” to 14”,  would entail a major rework of previous designs, not the least to also provide suitable protection against the new caliber. There was, however, considerable debate over whether to improve gun caliber or not. There would be major problems designing a ship to fit a 14” gun, since a new gun design would entail construction of a warship without knowing the final use of the gun; if the design of the gun failed, the fleet would be stuck with a ship of no improvement over its predecessors and possibly a major step back, since at most, ten 12” guns would then be fitted.

    Detailed designs were submitted and the General Board, arguing that commonality and a lack of precedence for the heavier caliber in foreign navies precluded the use of the 14” ship at the moment, ordered a six-turret, 12” artillery version to go ahead. At the same time, both a new 12” gun and the 14” gun were being developed, so future battleships would be able to use a different, more advanced weapon.

    When authorized by Congress on March 3rd 1908, these two vessels, Wyoming and Arkansas, represented the largest dreadnoughts yet to be build.
The new design represented several new ideas that were partially drawn from the sortie of the Great White Fleet around the world, notably the placement of the secondary artillery, which had been placed too low in previous vessels. Now, they were mounted high above the sea amidships in an armored cassematte, with other, unarmored installations fore and aft.

    Armor positioning was at the most advanced phase outside of the famed all-or-nothing scheme utilized first in Nevada. Light armor protected the secondaries, a compromise made between the threat of detonating AP shells too early (and risking horrendous casualties in the superstructure) and the threat of HE from battleship secondaries and lighter vessels (which might destroy unprotected guns).

    Underwater protection was provided by the first U.S. torpedo protection bulkheads.

    Deck and belt armor designs had to wait until the final decision on the caliber of the main artillery, in the event the 12” gun.  As the theory of matching armor belts for a particular caliber in this case specified a 11” to 9” belt, that was what the designers gave Wyoming. The remaining armor, as well, was spread out according to the normal schemes.

    The Wyoming class only barely saw service in the Pacific War. The oldest class of battleships still in service at the time of Pearl Harbor, its members were not utilized in the battleline. In 1931, Wyoming was partially demilitarized, to be commissioned a training vessel (AG-17)  in May, 1931. She participated in amphibious training and in November 1941 became a AA training ship. In that role, she was vital in training able gunners for the many thousand AA guns spread throughout the fleet. She mounted all types of small weapons up to the 127mm L/38 dual-purpose artillery. Both visual and radar aiming methods could be exercised aboard her. She was decommisioned in August 1947 after 35 years of service.

    Arkansas, the other ship of the class, remained in active service with the U.S. fleet, but served the Atlantic Fleet and its predecessor organizations. She helped the Iceland landings, escorted convoys to the United Kingdom for defense against German raiders, and supported the Normandy and Southern France landings in 1944, before being sent to the Pacific. After a major overhaul, she participated in the Iwo Jima and Okinawa landings and ended her career during the Bikini A-bomb tests in 1946, sinking during the second, “Baker”, bombing.
 
Ships in class: 
AG-17, BB-32 Wyoming 
BB-33 Arkansas