Pennsylvania - class battleship The " Pennsylvania " class consisted of two super - dreadnought battleship s built for the United States Navy just before the First World War . The ships were named and , after the American states of the same names . They constituted the United States ' second battleship design to adhere to the " all or nothing " armor scheme , and were the newest American capital ship s when the United States entered the First World War . The s 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 guns and improved underwater protection . The class was the second standard type battleship class to join the United States Navy , along with the preceding and the succeeding , and classes . 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 . 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 . For the remainder of the inter - war period , the ships were used in exercises and fleet problem s . Both " Pennsylvania " and " Arizona " were present during the Japanese attack on Pearl Harbor . " 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 . 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 . " Pennsylvania " was severely damaged by a torpedo on 12 August 1945 , the day before the cessation of hostilities . With minimal repairs , she was used in Operation " Crossroads " , part of the Bikini atomic experiments , before being expended as a target ship in 1948 . Background . The preceding " Nevada " - class battleships represented a leap forward from previous American battleship technology and from most contemporary foreign designs . These ships were the first in the world to employ the " all or nothing " armor scheme that characterized every succeeding American battleship . 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 . The new system envisioned that , at long ranges , ships would be attacked with only armor piercing ( AP ) projectiles , stoppable only by heavy armor . Medium or light armor would only serve to detonate the shells . 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 . 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 . three guns mounted per turret . They were very unsatisfied with the awkward placement required on classes preceding the " Nevada " s , which had five and six two - gun turrets — yet moving back to the four two - gun turrets of the would be a significant loss in firepower . Although a triple turret was first proposed in American professional magazines in 1901 and briefly considered for the " South Carolina " s , it was not even in the experimental stage — the first turret was authorized in 1911 and would not be ready until months after contracts for the new ships would be signed with the shipbuilders . The decision to go ahead with the turret was a calculated gamble , but proved to be a qualified success : the only issue came with shell interference when the center and outside guns were fired simultaneously , which was easily solved by delaying the firing of the center barrel by a small fraction of a second . The major benefit , though , came from the weight savings from the reduction of an armored barbette and turret . These gains were used in heavier armor , making the " all or nothing " concept a reality . The " Nevada " s were also the first American battleships to use exclusively oil fuel , which had greater thermal efficiency than firing with coal or coal sprayed with oil . The cumulative effect of the change was measured by the navy as a fifty - five percent increase in steam production per pound of fuel ( in a design for an oil - fired version of the ) . This would give oil - fired vessels additional range , an important consideration for ships based in the Pacific Ocean , but the United States Navy ' s Bureau of Construction and Repair ( C & R ) pointed out what it saw as the unfortunate side effects , including a lower center of gravity , higher metacentric height , and the loss of coal bunkers , which were employed as part of the armor protection . However , just a few years later oil tanks below the waterline were considered indispensable parts of the underwater armor scheme employed in American dreadnoughts . Design . The General Board ' s call for a new 1913 fiscal year battleship design was sent in June 1911 with the recent " Nevada " innovations in mind . They desired a ship with a main battery of twelve 14 - inch guns in triple turrets , a secondary battery of twenty - two 5 - inch guns , a speed of , and armor equivalent to that of the " Nevada " s . C & R ' s first sketch was unsatisfactory ; their lengthy design of and actually had less armor than the " Nevada " s , with a belt . The design process was marked by various efforts to meet the General Board ' s specifications with only a moderate increase in tonnage over the " Nevada " class . Between January and March 1912 , thirteen sketches were prepared for consideration by C & R with reciprocating or turbine engines that traded either speed or metacentric height for armor . Some later designs gave up a half knot of speed to free up about , enough to thicken the belt from and the barbettes to . The choice between double or triple turrets was also still an issue , as the " Nevada " class had not been completed yet . The Bureau of Ordnance was in favor of waiting for test results , rather than risking reverting to two - gun 14 - inch turrets or moving up to two - gun 16 - inch turrets . In March 1912 , C & R proposed their seventh , eighth , ninth , and tenth designs to the General Board for approval . The eighth and ninth designs were the ones to give up a half knot of speed , while the tenth was a design with four triple turrets and lighter than the " Nevada " class ships . In April , the General Board chose the seventh design , which satisfied all of their requirements , albeit on the largest displacement , . The length was fixed at , the beam at , and the draft at . Steam turbines gave the design and , while the main armor belt was 13 . 5 inches tapering to at the ends . This design was further refined and emerged in a completed state in September . The delay was partially due to tests on the proposed armor , which were completed in June 1912 and resulted in significant alterations to the " Pennsylvania " class ' underwater protection . Specifications . The " Pennsylvania " - class ships were significantly larger than their predecessors , the . They had a waterline length of , an overall length of , a beam of ( at the waterline ) , and a draft of at deep load . This was longer than the older ships . Its designed standard and full load displacements were and , respectively , but they actually displaced standard and at full load , over more than the older ships . The class had a metacentric height of at full load . The ships had four direct drive Parsons steam turbine sets with geared cruising turbines , each of which drove a propeller in diameter . They were powered by twelve Babcock & Wilcox water - tube boilers . The turbines were designed to produce a total of , but only achieved during " Pennsylvania " s sea trials , when it slightly exceeded its designed speed of . However , " Pennsylvania " reached during full - power trials in 1916 , and " Arizona " reached in September 1924 . The class was designed to normally carry of fuel oil , but had a maximum capacity of . At full capacity , they could steam at a speed of for an estimated , though this could be extended to with a clean bottom . They had four turbo generator s . The " Pennsylvania " class carried twelve 14 - inch / 45 caliber ( 356 mm ) guns in triple gun turret s . The guns could not elevate independently and were limited to a maximum elevation of + 15° which gave them a maximum range of . The ships carried 100 shells for each gun . Defense against torpedo boat s was provided by twenty - two 5 inch 51 caliber ( 127 mm ) guns mounted in individual casemate s in the sides of the hull ; these proved vulnerable to sea spray and could not be worked in heavy seas . At an elevation of 15° , they had a maximum range of . Each gun was provided with 230 rounds of ammunition . The ships mounted four 3 inch 50 caliber ( 76 mm ) guns for anti - aircraft defense , although only two were fitted when completed . The other pair were added shortly afterward on top of Turret III . The class also mounted two 21 inch ( 533 mm ) torpedo tube s and carried 24 Bliss - Leavitt Mark 3 torpedo es for them . The " Pennsylvania " - class design continued the all - or - nothing principle of armoring only the most important areas of the battleships , which began in the preceding " Nevada " class . The waterline armor belt of Krupp armor measured thick and only covered the class ' machinery spaces and magazines . It had a total height of , of which was below the waterline ; beginning below the waterline , the belt tapered to its minimum thickness of . The transverse bulkheads at each end of the ships ranged from 13 to 8 inches in thickness . The faces of the gun turrets were thick while the sides were thick and the turret roofs were protected by of armor . The armor of the barbettes was thick . The conning tower was protected by of armor and had a roof eight inches thick . The main armor deck was three plates thick with a total thickness of ; over the steering gear the armor increased to in two plates . Beneath it was the splinter deck that ranged from in thickness . The boiler uptakes were protected by a conical mantlet that ranged from in thickness . A three - inch torpedo bulkhead was placed inboard from the side , and the class was provided with a complete double bottom . Testing in mid - 1914 revealed that this system could withstand of TNT . Authorization and construction . The authorization for the two " Pennsylvania " class ships faced political opposition for being too weak and expensive . Senator Benjamin Tillman believed that a much more capable warship was needed because of the shocking increase in battleship size over the previous few years — between 1907 ( the ) and 1912 , the displacement of American battleships increased by about fifty percent , from around to . Tillman proposed a " maximum battleship " in a Senate resolution in July 1912 , which was adopted unanimously : Tillman ' s proposal , however , was treated in his own words as a " joke " ; the " Advocate of Peace " stated that " it is nearly impossible to read this . . . without having an inextinguishable bout of laughter . " Still , C & R completed multiple studies of a maximum battleship constrained only by technological limitations . The first design submitted by C & R was a severely enlarged " Nevada " , or a ship with twelve 14 - inch guns , belt armor , and a maximum speed of for a price of $ 19 . 5 million . A later sketch dropped the speed to to see the effect on displacement and cost , which it dropped to and $ 17 million , respectively , and the consequent shortening of the ship would allow it to enter the dry docks in New York and Norfolk . Tillman was concerned with this speed , however , and another study increased the speed to , trading it for four 14 - inch guns , or one - third of the main battery , and much of the armor . Political opposition in Congress also made it difficult to build the " Pennsylvania " class . The United States ' House of Representatives refused to fund any new battleships for the fiscal year 1913 , though the Senate would fund two in its comparable bill . They eventually compromised on one , and the battleship that would become " Pennsylvania " was authorized on 22 August 1912 . The ship ' s plans were given to prospective builders on 20 December ; bids were opened on 18 February 1913 ; and the contract was awarded to the lowest bidder , Newport News , on 27 February 1913 at the quoted price of $ 7 , 260 , 000 without armor or armament . The independent bidding process led the navy to claim $ 750 , 000 in savings , but the final cost actually came in at $ 7 , 800 , 000 ( $ 15 , 000 , 000 with armor and armament ) . " Arizona " was the one approved battleship for the fiscal year 1914 . Secretary of the Navy George von Lengerke Meyer had requested three battleships for that fiscal year , citing the former policy of building two per year , plus an additional ship to make up for authorizing only " Pennsylvania " in the previous year , but congressional compromises once again approved only one new battleship . " Arizona " was authorized on 4 March 1913 , but to avoid a lengthy delay between the two , the ship was ordered much more quickly ( on 24 June ) by giving the contract to a navy - owned shipyard . " Pennsylvania " was laid down on 27 October 1913 , with goals of fourteen months until launch , and thiry - two until completion . The as - yet unnamed " Arizona " was laid down on the morning of 16 March 1914 with Assistant Secretary of the Navy Franklin Delano Roosevelt in attendance , and the builders intended to set a world - record ten months between keel - laying and launch , These ambitious goals — " Pennsylvania " s anticipated completion date was a full two months earlier than the American record — were set by Navy Secretary Josephus Daniels , who wanted the United States to compete with British and German building achievements . The constructors were not able not meet these goals , though . " Pennsylvania " was launched on 16 March 1915 — seventeen months from keel - laying to launch , and just over two - thirds complete — while " Arizona " was launched on 19 June 1915 , about fifteen months after keel laying . " Arizona " weighed at launch . Movie camera s were used to film the launch , in order to provide data for future launches . After their launch , both ships went through the necessary fitting - out period and sea trials . On " Pennsylvania " s trials , the ship attained a top speed of , averaged , and was also able to steam for twelve hours at in winds . These attributes pleased the navy ' s Board of Inspection , but " Scientific American " lamented the ship ' s low speed compared to the Italian s , Russian s , and British s , which they ( somewhat inaccurately ) stated had top speeds of , , and , respectively . " Pennsylvania " was commissioned on 12 June 1916 , its sister ship followed on 17 October 1916 . Service histories . " Pennsylvania " and " Arizona " were commissioned during the First World War , but prior to the United States ' entry on the side of the Allies . During their first year , the ships were cleaned and readied for full active duty . " Pennsylvania " became the flagship of the US Atlantic Fleet on 12 October 1916 . " Arizona " first fired its main guns on 23 December , but issues with the propulsion system , specifically a stripped turbine , kept the ship almost exclusively in the New York Navy Yard from December 1916 to March 1917 . Both ships were based in the United States for the duration of the war , owing to a shortage of fuel oil in the United Kingdom , and only the coal - burning battleships of Battleship Division Nine were sent . After the armistice , both " Pennsylvania " - class battleships were sent to the other side of the Atlantic . " Arizona " was sent first , leaving on 18 November and arriving in Portsmouth on the 30th . " Pennsylvania " escorted the American President Woodrow Wilson ' s transport , , across the Atlantic for the Paris Peace Conference in 1919 . In 1921 and 1922 , during the inter - war period , both ships took part in a mission to Peru and were transferred to the Pacific Fleet . " Pennsylvania " and " Arizona " were given extensive modernizations from 1929 through 1931 ; the expenditure came in the fiscal year 1930 . As part of the rebuilding , " Pennsylvania " , which had been designed as a fleet flagship , had its conning tower expanded . Aside from that , " Pennsylvania " and " Arizona " received similar treatment : the elevation of the main batteries was increased to , new fire control systems on tripod mast s were added , the secondary armament and directors were replaced and overhauled , ten 5 - inch anti - aircraft guns ( five per side ) were mounted on the weather deck which was above the secondary anti - ship 5 - inch gun battery , and their bridges were enlarged to hold elevated antiaircraft directors . Armor additions were comparatively minimal beyond anti - torpedo bulge s , which were standard additions on all major warships in this period : of armor were added to the second armored deck , and a torpedo bulkhead was added to the engine room . The propulsion system of the two " Pennsylvania " s received perhaps the most attention . The boiler system was entirely replaced with six small - tube boilers and new turbines , the latter partially from the canceled battleship . The new machinery allowed the ships to come close to their old design speed of , even with the added bulk of bulges : " Pennsylvania " made 20 . 89 knots and " Arizona " 20 . 7 knots on full - power trials . After their modernization , both ships participated in the normal activities of the fleet , including fleet problem exercises , and then joined the entire Pacific Fleet in their new base in Pearl Harbor , Hawaii , after the beginning of the Second World War in Europe . Two years later , on 7 December 1941 , the Japanese attack on Pearl Harbor sank " Arizona " in a tremendous explosion and slightly damaged " Pennsylvania " , which was in dry dock at the time . " Pennsylvania " came back into service more quickly than many of the other battleships present during the attack ; it left on 20 December and was under repair in San Francisco until 30 March 1942 . For the next several months , " Pennsylvania " was stationed on the United States ' West Coast , before being reassigned to Pearl Harbor as the fleet flagship for a short time ( August to October ) . After another refit in San Francisco , which lasted until February 1943 , the ship was sent to assist American forces engaged in the Aleutian Islands Campaign . During this time , " Pennsylvania " was nearly hit by a torpedo from , which was later sunk . For the next year , " Pennsylvania " was utilized in shore bombardment in the Battles of Makin , Kwajalein , Eniwetok , and Saipan , along with the Palau Islands Campaign . The ship also participated in the landings on Leyte and the Battle of Leyte Gulf . During this time , " Pennsylvania " was present at the last battle ever between battleships , the Battle of Surigao Strait . The ship did not fire any salvos because the Japanese vessels were turned away or sunk at long range , beyond " Pennsylvania " s outdated fire control but within range of other , radar - directed battleships . In 1945 , " Pennsylvania " was sent for another refit in San Francisco , and the guns in its main battery , worn out from the frequent shore bombardments , were replaced by those from " Nevada " and " Oklahoma " . After its completion in July , the ship bombarded Wake Island on 1 August en route to Okinawa , where it was struck by an air - dropped torpedo . It hit near the starboard propeller shaft , killing twenty men and knocking out three of the ship ' s four shafts . The area near the shafts , though , was also a vital area , and the opened seals around the shafts led to large amounts of flooding that nearly sank the battleship . " Pennsylvania " was towed to shallower waters , where local repairs were made . The ship ' s last action was to fire at a " kamikaze " on 13 August , before it was towed to Guam beginning on the 18th , where temporary repairs were effected , before it was sent to Puget Sound for more permanent repairs . " Pennsylvania " arrived on 24 October only after a torturous journey , which saw the ship lose all but one of its remaining propeller shafts while taking on water through the temporary patch put over the torpedo hole in Guam . With the Japanese surrender on 2 September , the Puget Sound repairs were limited to those necessary to ensure " Pennsylvania " s delivery to Bikini Atoll for atomic experiments in July 1946 . The old battleship survived the tests , but was decommissioned on 29 August and used for radiological studies before being sunk as a target ship on 10 February 1948 . " Pennsylvania " was struck from the Navy Vessel Register nine days later .