In issuing desired specifications for the design that would become the Nevada class, the navy's General Board asked for triple gun turrets, i.e. By removing gun turrets and reducing the overall protected length of the ship, the navy's designers were able to devote the weight savings to the belt, as well as extra deck armor to protect against plunging shells. Medium or light armor would only serve to detonate the shells.
The new system envisioned that, at long ranges, ships would be attacked with only armor piercing (AP) projectiles, stoppable only by heavy armor. Devised with the knowledge that engagement ranges between battle fleets was growing greater as main battery sizes increased, the system moved away from previous designs that used heavy, medium, and light armor, in favor of using only heavy armor to protect vital areas on the ship. These ships were the first in the world to employ the " all or nothing" armor scheme that characterized every succeeding American battleship. The preceding Nevada-class battleships represented a leap forward from previous American battleship technology and from most contemporary foreign designs. Photograph courtesy of the National Archives and Records Administration. The Nevada class, represented here by Oklahoma in 1916, were the first American battleship class to utilize triple gun turrets, the " all or nothing" armor concept, oil fuel, and steam turbines with geared cruising turbines (albeit the latter only in Nevada) all of these innovations were continued in the Pennsylvania class. Main articles: Nevada-class battleship and Standard-type battleship
With minimal repairs, she was used in Operation Crossroads, part of the Bikini atomic experiments, before being expended as a target ship in 1948. Pennsylvania was severely damaged by a torpedo on 12 August 1945, the day before the cessation of hostilities. After a refit from October 1942 to February 1943, Pennsylvania went on to serve as a shore bombardment ship for most of the remainder of the war, an exception being the October 1944 Battle of Surigao Strait, the last battle ever between battleships. Arizona was sunk in a massive magazine explosion and was turned into a memorial after the war, while Pennsylvania, in dry dock at the time, received only minor damage. Both Pennsylvania and Arizona were present during the Japanese attack on Pearl Harbor. For the remainder of the inter-war period, the ships were used in exercises and fleet problems. Both were sent across the Atlantic to France after the war for the Paris Peace Conference of 1919, and were then transferred to the Pacific Fleet before being significantly modernized from 1929 to 1931. In service, the Pennsylvania class saw limited use in the First World War, as a shortage of oil fuel in the United Kingdom meant that only the coal-burning ships of Battleship Division Nine were sent.
The class was the second standard type battleship class to join the United States Navy, along with the preceding Nevada and the succeeding New Mexico, Tennessee and Colorado classes. The Nevada-class battleships represented a marked increase in the United States' dreadnought technology, and the Pennsylvania class was intended to continue this with slight increases in the ships' capabilities, including two extra 14-inch (360 mm) guns and improved underwater protection. They constituted the United States' second battleship design to adhere to the " all or nothing" armor scheme, and were the newest American capital ships when the United States entered the First World War. The ships were named Pennsylvania and Arizona, after the American states of the same names. The Pennsylvania class consisted of two super-dreadnought battleships built for the United States Navy just before the First World War. Photograph courtesy of the National Archives and Records Administration.Ħ00 ft (182.9 m) (waterline) 608 ft (185.3 m) (overall)ġ2 Babcock & Wilcox water-tube boilers, replaced by 6 Bureau Express boilers (5 Bureau Express and 1 White-Forster in Pennsylvania) in 1929-31 refitĦ,070 nmi (11,240 km 6,990 mi) at 12 knots (22 km/h 14 mph) Arizona at the United States' post-First World War naval review in New York, December 1918.