The Alaska class were six very large cruisers ordered before World War II for the United States Navy, of which only two were completed and saw service late in the war. The US Navy designation for the ships of this class was 'large cruiser' (CB) and the majority of leading reference works consider them as such. However, various other works have alternately described these ships as battlecruisers despite the US Navy having never classified them as such. The Alaskas were all named after territories or insular areas of the United States, signifying their intermediate status between larger battleships (which were mostly named after states) and smaller heavy and light cruisers (which were named after cities).
The idea for a large cruiser class originated in the early 1930s when the U.S. Navy sought to counter the "pocket battleships" being launched by Germany. Planning for ships that eventually evolved into the Alaska class began in the late 1930s after the deployment of Germany's s and rumors that Japan was constructing a new large cruiser class, the B-65 cruiser. 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 .
Of the six planned, and were the only two to be completed; a third, Hawaii, was still building at the war's end and had its construction suspended on 16 April 1947, while the remaining three were cancelled. Alaska and Guam 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.
Background
Heavy cruiser development formalized between World War I and World War II due to the terms of the Washington Naval Treaty and successor treaties and conferences, where the United States, Britain, Japan, France, and Italy agreed to limit heavy cruisers to 10,000 tons displacement with 8-inch main armament. Up until the Alaska class, US cruisers designed between the wars followed this pattern.
The initial impetus for the Alaska design came from the deployments of Germany's so-called pocket battleships in the early 1930s. Though no actions were immediately taken, these thoughts were revived in the late 1930s when intelligence reports indicated Japan was planning or building "super cruisers" of the B-65 class that would be much more powerful than the current US heavy cruisers. The navy responded in 1938 when the General Board asked the Bureau of Construction and Repair to conduct a "comprehensive study of all types of naval vessels for consideration for a new and expanded building program". The US 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. While these claims are difficult to verify, others have speculated that their design was "politically motivated" rather than strategic.
Design
One historian described the design process of the Alaska class as "torturous" due to the numerous changes and modifications made to the ship's layouts by numerous departments and individuals. Indeed, there were at least nine different layouts, ranging from 6,000-ton anti-aircraft 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 such that they were vulnerable, by comparison with a battleship, to torpedoes and to shells that fell short of the ship. The final design was a scaled-up 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 Alaskas were officially funded in September 1940 along with a plethora of other ships as a part of the Two-Ocean Navy Act. Their role had been altered slightly: in addition to their surface-to-surface role, they were planned to protect carrier groups. This carrier escort capability was favored by Admiral King. Because of their bigger guns, greater size and increased speed, they would be more valuable in this role than heavy cruisers, and would provide insurance against reports that Japan was building super cruisers more powerful than the American heavy cruisers. The escort concept would also free the few existing heavy cruisers for scouting (their original purpose).