Brooklyn-class cruiser

The Brooklyn-class cruiser was a class of nine light cruisers built for the United States Navy between 1935 and 1938. Armed with five triple 6-inch (152 mm) gun turrets (three forward, two aft), they mounted more main battery guns than any other standard US cruiser. The Brooklyn-class ships were all commissioned between 1937 and 1939, in the time between the start of the Second Sino-Japanese War and before the invasion of Poland. They served extensively in both the Pacific and Atlantic theaters during World War II.

Helena was sunk in the Pacific, and while some of the others were heavily damaged, the remaining ships of the class were decommissioned shortly after the end of the war. Six were transferred to South American navies in 1951, where they served for many more years. One of these, ARA General Belgrano, formerly Phoenix, was sunk during the Falklands War in 1982.

The Brooklyn-class ships had a strong influence on US cruiser design. Nearly all subsequent US cruisers, heavy and light, were directly or indirectly based on them. Notable among these are the Cleveland-class light cruiser and Baltimore-class heavy cruiser of World War II.

The Brooklyn-class design was a further refinement of the New Orleans-class heavy cruiser that preceded it. The desire for the Brooklyns arose from the London Naval Treaty of 1930, which limited the construction of heavy cruisers, i.e., ships carrying guns with calibers between 6.1 and 8 inches (155 and 203 mm). Great Britain needed trade control cruisers and hoped that the treaty would limit nations to smaller cruisers with a 6,000-to-8,000-long-ton (6,096 to 8,128 t) range that she could afford. Agreement to the London Treaty and the proceeding with the American light cruiser design can be focused to Admiral William V. Pratt, who overrode the vehement objections of the General Board.

Under the treaty the US was allowed 180,000 long tons (182,888 t) for 18 heavy cruisers and 143,500 long tons (145,803 t), with no limit on the number of ships, for light cruisers. The United States needed large cruisers to deal with the extreme ranges that operations in the Pacific Ocean required. Cruisers with 6-inch (150 mm) guns and 10,000 long tons (10,160 t) were therefore desired. The US Navy's experience with the Omaha class was not all that could be hoped for. Their light hull design caused a stressed hull and was very overweight.

Design started in 1930, with the first four of the class ordered in 1933, and an additional three ships in 1934. Basic criteria had been that speed and range should match heavy cruisers, and when the Japanese Mogami class carrying fifteen 6-inch main guns appeared, the new US ships would match their weaponry. Various combinations of armor and power plants were tried in the efforts to stay below the Treaty 10,000 ton limit. Aviation facilities were moved to the stern of the ship from the amidships position of the New Orleans-class cruisers.

From 1942, the bridge structure was lowered and radar was fitted.

The last two ships of the class, St. Louis and Helena, were slightly modified versions of the design with new higher pressure boilers and a unit system of machinery that alternated boiler and engine rooms to prevent a ship from being immobilized by a single unlucky hit; this system would be used in all subsequent US cruisers. Additionally, AA armament was improved. They were the first US cruisers to be armed with twin 5-inch (127 mm)/38-caliber guns. They could be distinguished visually from the other Brooklyns by the placement of the after deckhouse, immediately abaft the second funnel, and by the twin 5-inch mounts.