Alaska - class cruiser The " Alaska " - class cruisers were a class of six cruisers ordered prior to World War II for the United States Navy . Officially the Navy classed them as Large Cruisers ( CB ) , although others have regarded them as battlecruisers . Their intermediate status is reflected in their names relative to typical U . S . battleship and cruiser practices : all being named after " territories or insular area s " of the United States . Of the six planned only three were laid down ; two were completed and the third ' s construction was suspended on 16 April 1947 when she was 84 % complete . and served with the U . S . Navy for the last year of World War II as bombardment ships and fast carrier escorts . They were decommissioned in 1947 after spending only 32 and 29 months in service , respectively . The idea for a large cruiser class originated in the early 1930s when the U . S . Navy sought to counter " Deutschland - class " " pocket battleships " being launched by Germany . Planning for ships that eventually evolved into the " Alaska " class began in the later 1930s after the deployment of Germany ' s s and rumors that Japan was constructing a new battlecruiser class . To serve as " cruiser - killers " capable of seeking out and destroying these post - Treaty heavy cruisers the class was given large guns of a new and expensive design , limited armor protection against 12 - inch shells , and machinery capable of speeds of about 31 – 33 knots ( 36 – 38 mph , 58 – 61 km / h ) . Background . Heavy cruiser development was steadied between World War I and World War II by the terms of the Washington Naval Treaty and successor treaties and conferences . In this treaty , the United States , Britain , Japan , France , and Italy had agreed to limit heavy cruiser s to 10 , 000 tons displacement with 8 - inch main armament . Up until the " Alaska " class , U . S . cruisers designed between the wars followed this pattern . The initial impetus for the design of the " Alaska " class came from the deployments of the so - called pocket battleships in the early 1930s . Though no actions were taken immediately , plans were revived in the late 1930s when intelligence reports indicated Japan was planning or building " super cruisers " which were much more powerful than U . S . heavy cruisers . The navy responded in 1938 , when a request from the General Board was sent to the Bureau of Construction and Repair for a " comprehensive study of all types of naval vessels for consideration for a new and expanded building program " . The U . S . President at the time , Franklin Delano Roosevelt , may have taken a lead role in the development of the class with his desire to have a counter to raiding abilities of Japanese cruisers and German pocket battleships , which had led to them being called " politically motivated " , but these claims are difficult to verify . Design . One historian described the design process of the " Alaska " class as " torturous " due to the numerous changes and modifications made to the ships ' layouts by numerous departments and individuals . Indeed , plans resulted in at least nine different layouts , ranging from 6 , 000 - ton antiaircraft cruisers to " overgrown " heavy cruisers and a 38 , 000 - ton mini - battleship that would have been armed with twelve 12 - inch and sixteen 5 - inch guns . The General Board , in an attempt to keep the displacement under 25 , 000 tons , allowed the designs to offer only limited underwater protection . As a result , the " Alaska " class , when built , were vulnerable to torpedoes and shells that fell short of the ship . The final design chosen was a scaled - up " Baltimore " class that had the same machinery as the s . This ship combined a main armament of nine 12 - inch guns with protection against 10 - inch gunfire into a hull that was capable of . The new class was officially funded in September 1940 along with a plethora of other ships as a part of the Two - Ocean Navy Act . The new ships ' role had been altered slightly ; in addition to their surface - to - surface role , they were planned to protect carrier groups . Because of their bigger guns , greater size and increased speed , they would be more valuable in this role than heavy cruisers , and they would also provide insurance against reports that Japan was building super cruisers more powerful than U . S . heavy cruisers . Possible conversion to aircraft carriers . Yet another drastic change was considered during the " carrier panic " of late 1941 . At this point , the Navy and the President realized that the United States needed more aircraft carrier s as quickly as possible . As a result , the Bureau of Ships decided to convert a few hulls that were currently under construction to carriers . At different times , they considered converting parts or all of the light cruiser s , the heavy cruiser s , the " Alaska " class , or even one of the s ; in the end , they chose the " Cleveland " s , resulting in the conversion of nine ships under construction at the New York Shipbuilding Corporation shipyard , Camden , New Jersey as the light aircraft carriers comprising the . A conversion of the " Alaska " cruisers to carriers was " particularly attractive " because of the many similarities between the design of the s and the " Alaska " class , including the same machinery . However , when " Alaska " cruisers were compared to the " Essex " carriers , converted cruisers would have had a shorter flight deck ( so they could have carried only 90 % of the aircraft ) , would have been lower in the water , and could travel fewer at . In addition , the large cruiser design did not include the massive underwater protections found in normal carriers due to the armor weight devoted to counter shell fire . Lastly , an " Alaska " conversion could not satisfy the navy ' s goal of having new aircraft carriers quickly , as the work needed to modify the ships into carriers would entail long delays . With these in mind , all planning involved with converting the " Alaska " s was ended on 7 January 1942 . Construction . Of the six " Alaska " - class cruisers that were planned , only three were laid down . The first two , and , were completed . Construction of , the third , was suspended on 16 April 1947 when she was 84 % complete . The last three , " Philippines " , " Puerto Rico " , and " Samoa " , were delayed since all available materials and slipways were allocated to higher priority ships , such as aircraft carriers , destroyer s , and submarine s . Construction had still not begun when steel shortages and a realization that these " cruiser - killers " had no more cruisers to hunt — as the fleets of Japanese cruisers had already been defeated by aircraft and submarines — made the ships " white elephants " . As a result , construction of the last three members of the class never began , and they were officially canceled on 24 June 1943 . Service history . and served with the U . S . Navy during the last year of World War II . Similar to the fast battleship s , their speed made them useful as shore bombardment ships and fast carrier escorts . Both protected when she was on her way to be repaired in Guam after being hit by two Japanese bombs . Afterward , " Alaska " supported the landings on Okinawa , while " Guam " went to San Pedro Bay to become the leader of a new task force , Cruiser Task Force 95 . " Guam " , joined by " Alaska " , four light cruisers , and nine destroyers , led the task force into the East China and Yellow Seas to conduct raids upon shipping ; however , they only encountered Chinese junks . By the end of the war , the two had become celebrated within the fleet as excellent carrier escorts . After the war , both ships were decommissioned and " mothballed " in 1947 after having spent 32 and 29 months in service , respectively . In 1958 , the Bureau of Ships prepared two feasibility studies to explore whether " Alaska " and " Guam " could be suitably converted into guided - missile cruiser s . The first study involved removing all of the guns in favor of four different missile systems . At $ 160 million , this proposed removal was seen as cost - prohibitive , so a second study was initiated . The study left the forward batteries ( the two 12 - inch triple turrets and three of the 5 - inch dual turrets ) unchanged , and added a reduced version of the first plan on the stern of the ship . Even though the proposals would have cost approximately half as much as the first study ' s plan ( $ 82 million ) , it was still seen as too expensive . As a result , both ships were stricken from the Naval Vessel Register on 1 June 1960 . " Alaska " was sold for scrap on 30 June 1960 , and " Guam " on 24 May 1961 . The still - incomplete was considered for a conversion to be the Navy ' s first guided - missile cruiser for a time ; this thought lasted until 26 February 1952 , when a different conversion to a " large command ship " was contemplated . In anticipation of the conversion , her classification was changed to CBC - 1 . This would have made her a " larger sister " for , but a year and a half later ( 9 October 1954 ) she was re - designated CB - 3 . " Hawaii " was stricken from the Naval Vessel Register on 9 June 1958 and was sold for scrap in 1959 . " Large cruisers " or " battlecruisers " ? Early in its development , the class used the designation CC , which signified that they were to be battlecruisers in the tradition of the ; however , the designation was later changed to CB to reflect their new name , " large cruiser " , and the practice of referring to them as battlecruisers was officially discouraged . The U . S . Navy then named the individual vessels after U . S . territories , rather than states ( as was the tradition with battleships ) or cities ( for which cruisers were named ) , to symbolize the belief that these ships were supposed to play an intermediate role between heavy cruisers and fully - fledged battlecruiser s . The " Alaska " - class resembled contemporary battleships ( particularly the " North Carolina " - class , " South Dakota " - class , and " Iowa - class " ) in appearance , mounted the familiar 2 - A - 1 main battery , and shared a similar massive columnar mast . They displaced twice that of the newest heavy cruisers ( the " Baltimore " class ) . and only 5 , 000 tons less than the London Treaty battleship standard displacement limit of 35 , 000 long tons ( 36 , 000 t ) . They were also longer than several treaty battleships such as the " King George V " and " North Carolina " classes . In design and armor the " Alaska " class are regarded as " large cruisers " rather than battlecruisers . Their design was ' from the keel up , just a scaled - up treaty cruiser unencumbered by the Washington , London and Second London naval treaties , not derived from a battleship ( as World War I battlecruisers were ) . In common with U . S . heavy cruisers , they had aircraft hangars and a single large rudder . Their armor lacked the underwater protection systems found on intermediate capital ships ( described alternatively as battlecruisers or small battleships ) such as the " Dunkerque " and " Scharnhorst " classes and full - fledged battleships . This left the " Alaskas " virtually defenseless against torpedoes , as well as vulnerable to shells falling slightly short of their mark and continuing underwater to hit the hull . While the " Alaskas " had more side armor than other contemporary U . S . cruisers , their protection was only marginally capable of stopping 12 " fire ; they were vulnerable to battleship fire ( 14 – 16 " fire ) at any range . In addition , despite being much larger than the " Baltimore " class , the numbers of secondary and anti - aircraft batteries of the " Alaskas " was similar . Whereas the " Alaska " class carried twelve 5 " / 38 caliber in six twin turrets , fifty - six 40 mm , and thirty - four 20 mm guns , the " Baltimore " class carried the same number of 5 " / 38s , eight fewer 40 mm , and only ten fewer 20 mm . , considerably fewer than new U . S . battleships that had ten ( save for " South Dakota " ( BB - 57 ) ) 5 " / 38 twin mounts while older refitted U . S . battleships had eight . Author Richard Worth remarked that when they were finally completed , launched , and commissioned , they had the " size of a battleship but the capabilities of a cruiser " . The " Alaska " - class was similarly expensive to build and maintain as contemporary battleships yet far less capable due to armor deficiencies , while only able to put up a comparable anti - aircraft defense as the much cheaper " Baltimore " cruisers . Despite these cruiser - like characteristics , and the U . S . Navy ' s insistence on their status as cruisers , the " Alaska " class were frequently described as battlecruisers at the time . The official navy magazine " All Hands " said " The " Guam " and her sister ship " Alaska " are the first American battle cruisers ever to be completed as such . " Some modern historians take the view that this is a more accurate designation because they believe that the ships were " in all sense of the word , battlecruisers " , with all the vulnerabilities of the type . The traditional Anglo - American battlecruiser concept had always sacrificed protection for the sake of speed and armament , meaning they were not intended to stand up against the guns they themselves carried . The " Alaska ' s " percentage of armor tonnage , 28 . 4 % , was slightly less than that of fast battleship s ; the British " King George V " class , the American , and the battlecruiser / fast battleship all had armor percentages between 32 and 33 % , whereas the " Lexington " - class battlecruiser design had a nearly identical armor percentage of 28 . 5 % . In fact , older battlecruisers , such as the ( 19 . 9 % ) , had a significantly " lower " percentage . Armament - wise , they had much larger guns than contemporary heavy cruisers ; while the " Baltimore " class only carried nine 8 " / 55 caliber Marks 12 and 15 guns , < ref name = " 8 / 55 12 and 15 " > < / ref > the " Alaska " class carried nine 12 " / 50 caliber gun s that were as good as , if not superior to , the old 14 " / 50 caliber gun used on the U . S . Navy ' s pre - treaty battleships , < ref name = " 12 / 50 " > < / ref > Armament . Main battery . As built , the " Alaska " class had nine 12 " / 50 caliber Mark 8 guns mounted in three triple ( 3 - gun ) turrets , with two turrets forward and one aft , a configuration known as " 2 - A - 1 " . The previous 12 " gun manufactured for the U . S . Navy was the Mark 7 version , which had been designed for and installed in the 1912 s . The Mark 8 was of considerably higher quality ; in fact , it " was by far the most powerful weapon of its caliber ever placed in service . " Designed in 1939 , it weighed , including the breech , and could sustain an average rate of fire of 2 . 4 – 3 rounds a minute . It could throw a Mark 18 armor piercing shell at an elevation of 45° , and had a 344 - shot barrel life ( about 54 more than the much larger but similar 16 " / 50 caliber Mark 7 gun found in the " Iowa " battleships . ) . The turrets were very similar to those of the " Iowa " - class battleships , but differed in several ways ; for example , the " Alaska " - class had a two - stage powder hoist , instead of " Iowa " - class ' s one - stage hoist . These differences made operating the guns safer and increased the rate of fire . In addition , a " projectile rammer " was added to " Alaska " and " Guam " . This machine transferred shells from storage on the ship to the rotating ring that fed the guns . However , this feature proved unsatisfactory , and it was not planned for " Hawaii " or any subsequent ships . Because " Alaska " and " Guam " were the only two ships to mount these guns , only ten turrets were made during the war ( three for each ship including " Hawaii " and one spare ) . They cost $ 1 , 550 , 000 each and were the most expensive heavy guns purchased by the U . S . Navy in World War II . Secondary battery . The secondary battery of the " Alaska " class was composed of twelve dual - purpose ( anti - air and anti - ship ) 5 " / 38 caliber gun s in twin mounts , with four offset on each side of the superstructure ( two on each beam ) and two centerline turrets fore and aft . The 5 " / 38 was originally intended for use on only destroyer s built in the 1930s , but by 1934 and into World War II it was being installed on almost all of the U . S . ' s major warships , including aircraft carriers , battleships , and heavy and light cruisers . < ref name = " 5 / 38 " > < / ref > Anti - aircraft battery . For anti - aircraft armament , the " Alaska " - class ships carried 56 x 40 mm guns and 34 x 20 mm guns . These numbers are comparable to 48 x 40 mm and 24 x 20 mm on the smaller " Baltimore " class heavy cruisers and 80 x 40 mm and 49 x 20 mm on the larger " Iowa " battleships . Arguably the most efficient light anti - aircraft gun of World War II , the 40 mm Bofors was used on nearly every major warship in the U . S . and UK fleets during World War II from about 1943 to 1945 . Although they were a descendant of German and Swedish designs , the Bofors mounts used by the United States Navy during World War II had been heavily " Americanized " , which brought the guns up to U . S . Navy standards . This new standard resulted in a gun system set to English standards ( now known as the Standard System ) with interchangeable ammunition , simplifying the logistics situation for World War II . When coupled with hydraulic couple drives to reduce salt contamination and the Mark 51 director for improved accuracy , the 40 mm Bofors became a fearsome adversary , accounting for roughly half of all Japanese aircraft shot down between 1 October 1944 and 1 February 1945 . The Oerlikon 20 mm anti - aircraft gun was one of the most extensively used anti - aircraft guns of World War II ; the U . S . alone manufactured a total of 124 , 735 of these guns . When activated in 1941 , they replaced the 0 . 50 " M2 Browning machine gun on a one - for - one basis . The Oerlikon gun remained the primary anti - aircraft weapon of the United States Navy until the introduction of the 40 mm Bofors in 1943 .