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 in 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.

USS Helena (CL-50) 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 USS Phoenix (CL-46), 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.

Design
The Brooklyn-class design was a further refinement of the New Orleans-class cruiser 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 in. Great Britain needed trade control cruisers and hoped that the treaty would limit nations to smaller cruisers with a 6000 to 8000 LT 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 180000 LT for 18 heavy cruisers and 143500 LT, 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 in guns and 10000 LT were therefore desired. The US Navy's experience with the Omaha-class cruiser was not all that could be hoped for. The 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 cruiser 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.

St. Louis subclass
The last two ships of the class, USS St. Louis (CL-49) and USS Helena (CL-50), 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.

Armament
The Brooklyn class was equipped with 15 6-inch/47 caliber Mark 16 naval guns, developed from the 6-inch/53 caliber Mark 8 used on the Omaha-class cruiser. The decision was reached as the gun could achieve up to ten rounds per minute rate of fire. This gave the class the ability to send up to 150 rounds a minute at its intended target. This allowed the cruiser to smother an enemy ship with fire. The turret arrangement was five turrets, each mounting three guns on a single sleeve, which did not allow the guns in a turret to move independently. The 6-inch guns were of a new design, the Mark 16, which could fire a 130 lb armor-piercing shell (AP) up to 26100 yd with twice the penetrative power of the old gun. The ammunition was of the semi-fixed type. The impact of the shell changed the General Board's view on the usefulness of light cruisers in service.

As designed, the anti-aircraft weaponry specified eight 5 in/25 caliber guns and eight .50 in caliber M2 Browning machine guns. The intention to mount 1.1 in/75 caliber anti-aircraft guns was frustrated and the requirement was not fully met until 1943. The weapon as deployed was less than satisfactory with frequent jamming and weight being serious issues. Some of the class had 5-in/38 caliber guns installed versus the 5-in/25 guns. There were varied mixes of 20 mm Oerlikon cannons and 40 mm Bofors gun mountings actually installed during World War II, 28 40 mm (4 × 4, 6 × 2) and twenty 20 mm (10 × 2) being the most common.

Fire control
The Brooklyn class was deployed with the Mark 34 director and later the Mark 3 radar. This would be upgraded to the Mark 8 and again to the Mark 13 radar. The secondary battery was controlled by the Mark 28 and upgraded to the Mark 33 fire control systems. The associated radars were the Mark 4 fire control radar and upgraded again to the Mark 12. Two anti-aircraft fire directors were fitted to each ship. A late World War II refit saw the Mk 51 director installed for the Bofors guns. Night engagements were improved when in 1945, the Mark 57 and 63 directors were installed.

Successors
The vast majority of cruisers built by the United States during World War II derive from the Brooklyn design. Modifications of the Brooklyn-class hull were the predecessors to the two main lines of wartime cruisers, respectively the Cleveland-class cruiser light cruiser armed with 6-inch guns and Baltimore-class cruiser heavy cruiser armed with 8-inch guns. The third line, the Atlanta-class cruiser light cruiser armed with 5-inch guns, shared the same unit system of machinery arrangement as the other two lines, but on a smaller hull with two shafts instead of four.

The Brooklyn class would lead to the Cleveland-class light cruiser (less a fifth triple 6-inch turret), which then led to the Fargo-class cruiser and finally the Worcester-class cruiser. The other successor was USS Wichita (CA-45), built on a modified Brooklyn-class hull, with a heavy cruiser armament featuring three rather than five triple turrets, but each turret containing larger 8-inch guns, and increased armor. Wichita was succeeded by the Baltimore class and the later Oregon City-class cruiser class, and finally the upgraded Des Moines-class cruiser. The Atlanta class would be succeeded by the Juneau-class cruiser and then almost by the cancelled CL-154-class cruiser. As the Baltimore class began building about a year after the Cleveland class, later Cleveland developments and improvements were incorporated into the Baltimore-class hull.

Finally, both Cleveland and Baltimore hulls were converted to light aircraft carriers. The Independence-class aircraft carrier of light aircraft carriers, were converted from Cleveland-class cruisers under construction, and the Saipan-class aircraft carrier light carriers used the basic form of the Baltimore-class cruiser design.

War service
Several Brooklyns were seriously damaged during World War II, although all but one of the cruisers survived. USS Boise (CL-47) was severely damaged by a shell that hit her forward turret magazine during the Battle of Cape Esperance on 11 October 1942, suffering many casualties, but the magazine (being partially flooded as a result of shell hits in her hull) did not explode. USS Nashville (CL-43) was hit by a kamikaze attack on 13 December 1944, off Mindoro, which killed or wounded 310 crewmen. USS Honolulu (CL-48) was torpedoed at the Battle of Kolombangara on 12–13 July 1943, as was her near-sister USS St. Louis (CL-49). After being repaired in the United States, Honolulu returned to service only to be torpedoed by a Japanese aircraft on 20 October 1944, during the invasion of Leyte. On 11 September 1943, USS Savannah (CL-42) was hit by a German Fritz X radio guided bomb which penetrated her #3 turret and blew out the bottom of the ship. Skillful damage control by her crew saved her from sinking. While under repair in the United States, Savannah and Honolulu were rebuilt with a bulged hull that increased their beam by nearly 8 ft and their 5-inch/25 caliber guns were replaced by four twin 5-inch/38 caliber guns, although the repairs to Savannah were completed too late for her to see frontline action again.

Helena was sunk in 1943 during the Battle of Kula Gulf. The remains of the ship were discovered below the surface of New Georgia Sound by Paul Allen's research ship RV Petrel in April 2018. St. Louis was seriously damaged twice, but survived the war.

Post-war
All ships of the class went into reserve in 1946-47. Six were sold to South American countries in the early 1950s, and served for many more years: Brooklyn and Nashville to Chile, St. Louis and Philadelphia to Brazil, and Boise and Phoenix to Argentina. Savannah and Honolulu remained in reserve until struck in 1959. ARA General Belgrano (ex-Phoenix) was torpedoed and sunk by HMS Conqueror (S48) during the Falklands War, while CHILEAN CRUISER O'Higgins (ex-Brooklyn) remained in service with the Chilean Navy until 1992. She sank under tow, on her way to the scrappers, in the mid-Pacific in 1992.