Atlanta-class cruiser

The Atlanta-class cruisers were eight United States Navy light cruisers originally designed as fast scout cruisers or flotilla leaders, but later proved to be effective anti-aircraft cruisers during World War II. They were also known as the Atlanta-Oakland class. The Oakland and later ships had slightly different armament as they were further optimized for anti-aircraft fire. With 8 dual 5 inch/38 caliber (127 mm) gun mounts (8x2 5-inch guns), the first run of Atlanta-class cruisers had by far the heaviest anti-aircraft armament of any cruiser of World War II.

Two ships of this class were sunk in action: USS Atlanta (CL-51) and USS Juneau (CL-52). The other six were deactivated shortly after the war and were scrapped in the 1960s.

Specifications
The original main gun battery of the Atlanta-class was composed of eight dual 5 inch/38 caliber (127 mm) gun mounts (8x2 5-inch guns). This battery could fire over 17,600 pounds (10,560 kg) of shells per minute, including the radar-fuzed "VT" antiaircraft shells. Four of the ships, beginning with USS Oakland (CL-95), had their two "wing" mounts of dual 5 inch guns replaced with eight of the highly effective Bofors 40 mm anti-aircraft guns. The Atlanta-class cruisers were the only class of U.S. Navy cruisers commissioned during World War II to be armed with torpedoes tubes, with eight 21" torpedo tubes in two quad launchers.

The class was designed with a substantial secondary anti-aircraft armament of sixteen 1.1 in guns in quad mounts, later replaced by 40 mm anti-aircraft guns, and 6 20 mm rapid-fire anti-aircraft cannons. More of these weapons were added as the war progressed to counter the danger of Japanese air attacks (especially kamikazes). Oakland was launched with eight Bofors 40 mm guns and sixteen 20 mm anti-aircraft cannons. Although ships of the class were planned as destroyer flotilla leaders, the original design did not include anti-submarine armament such as sonar or depth charge tracks; these were added later. When the vessels were determined to be more valuable as protection against aircraft, the tracks were removed.

The class was powered by four 665 psi boilers, connected to 2 geared steam turbines producing 75000 hp, and the ships could maintain a top speed of 33.6 kn. On trial the Atlanta made 33.67 kn and 78,985 SHP. The ships of the Atlanta-class had thin armor: a maximum of 3.5 in (88.9 mm) on their sides, with the captain's bridge and the 5-inch gun mounts being protected by only 1.25 in (31.75 mm).

The ships were originally designed for 26 officers and 523 men, but this increased to 35 officers and 638 men with the first four ships, and 45 officers and 766 men with the second group of four ships beginning with Oakland. The ships were also designed as flagships with additional space for a flag officer and his staff but the additional space was used for additional crew necessary to man anti-aircraft weapons and electronics.

Criticisms
Although very formidable as anti-aircraft ships, the Atlanta-class cruisers did not fare well in surface combat. The only two cruisers of the class that engaged in surface combat were sunk: the Atlanta and the Juneau. The U.S. Navy lost three light cruisers during World War II, two which were Atlantas. Both were sunk in surface combat during the Guadalcanal Campaign. It should be noted, however, that both of these vessels received their fatal blows from Japanese torpedoes, and gunfire from larger, more heavily armed ships. The unique armament of the Atlanta-class did not contribute to their loss.

The Atlanta-class design was also criticized for its shortage of gunfire directors for the main 5-inch gun battery, which reduced its effectiveness. Initially there were not enough intermediate anti-aircraft guns (i.e. 1.1 in guns, Bofors 40 mm and the Oerlikon 20 mm rapid-fire cannons). These problems were somewhat corrected in naval shipyards by the end of 1942, but the Atlanta-class warships were thereafter overloaded with weight, compared to the size of their hulls, and throughout World War II and the postwar years, they had problems with topside weight which was addressed by a redesign of the third repeat order which was called the Juneau-class.

Service history
All eight ships in this class served during World War II, and six ships survived the war. The lead ship of this class, the USS Atlanta (CL-51), was laid down on 22 April 1940 and launched on 6 September 1941. Atlanta was commissioned at the New York Navy Yard on 24 December 1941, just a few weeks after the Japanese attack on Pearl Harbor of 7 December. Atlanta participated as an anti-aircraft cruiser in the decisive American victory at the Battle of Midway in June 1942 before she was sent south to fight in the Solomon Islands. The USS Atlanta (CL-51) was scuttled after receiving a torpedo hit and heavy gunfire damage from IJN surface warships and USS San Francisco (CA-38) on 13 November 1942 during the Naval Battle of Guadalcanal. The USS Juneau (CL-52) was also heavily damaged in surface combat in the same battle and then sunk by Japanese submarine I-26, on 13 November 1942. USS Reno (CL-96) was torpedoed off Leyte on 4 November 1944 resulting in a large fire and significant flooding, but was saved from sinking by the damage control efforts of the crew.

After the war, the six surviving ships in this class were decommissioned between 1947 and 1949 and placed in the reserve fleet. The ships received a new type designation of CLAA in 1949. None of this ships were recommissioned to serve in an active role; all were ultimately struck and scrapped by 1970.

Warships in this class

 * USS Atlanta (CL-51)
 * USS Juneau (CL-52)
 * USS San Diego (CL-53)
 * USS San Juan (CL-54)
 * USS Oakland (CL-95)
 * USS Reno (CL-96)
 * USS Flint (CL-97)
 * USS Tucson (CL-98)