In 1929, the United States Navy (USN) ordered a pair of new light cruiser warships for its all-new St. Louis-class. The series succeeded the earlier seven-strong Brooklyn-class and were intended as improvements to the design by installation of new high-pressure boiler units with a focus on combat survivability. Additionally, the new class was to shore up the anti-aircraft limitations inherent in the Brooklyn ships. The ships of the St. Louis-class became lead ship USS St. Louis (CL-49) and USS Helena (CL-50).
USS St. Louis (CL-49) was ordered on February 13th, 1929 and the contract awarded to Newport News Shipbuilding and Drydock Company of Virginia on October 16th, 1935. Her keel was laid down on December 10th, 1936 and she was launched to sea on April 15th, 1938. The warship was formally commissioned on May 19th, 1939.
As built, USS St. Louis displaced 10,000 tons under standard load and held a length of 608.7 feet with a beam of 61.4 feet and a draught of 24 feet. Installed power became 8 x Steam-based boiler units feeding 4 x Geared steam turbines outputting 100,000 horsepower to 4 x Shafts. The vessel could make headway at 32.5 knots.
Armament centered on a main battery of 15 x 6" guns held in five triple-gunned turrets. Three of these turrets were positioned forward of the superstructure and two were featured aft. The secondary battery consisted of 8 x 5" guns in twin-gunned mountings and served in the Anti-Aircraft (AA) role. There were also 8 x 0.50 caliber heavy machine guns fitted.
Armor protection ranged from 5" at the belt and 2" along the deck to 6" at the turret barbettes and 5" at the conning tower.
Aboard there was a crew of some 868 personnel that included a small air wing. The embarked aircraft were 4 x Curtiss SOC Seagull floatplanes which were launched via 2 x catapult systems located at the stern. These aircraft were recoverable by way of a crane. Full-service facilities ensured proper maintenance and repair was possible for these mission-critical aerial platforms.
Despite World War 2 (1939-1945) already having broken out in Europe on September 1st, 1939, the United States remained neutral in the early going so USS St. Louis was used mainly for Neutrality Patrols in Atlantic waters. She eventually passed through the Panama Canal to access the Pacific Ocean in November of 1940 and ended her voyage at Pearl Harbor, Hawaii where she was part of local patrols and exercises once on station there.
While moored in Hawaiian waters, USS St Louis was one of the ships present during the Japanese Attack on Pearl Harbor on December 7th, 1941. Her crew managed to get their AA guns active against the inbound enemy force as chaos reigned and several (three) Japanese attackers were shot down in the ensuing action. She managed to get underway at around 9:30AM and escaped the carnage in the harbor along with USS Detroit and USS Phoenix (USS St. Louis was the first large ship out of the harbor). Her luck at Pearl earned her the nickname of "Lucky Lou" for the entirety of her career with the United States Navy. Indeed, a Japanese midget submarine attempted a torpedo attack against her and these "fish" struck a nearby shoal instead.
Surviving Pearl, USS St. Louis remained active throughout the remainder of the Pacific Campaign. On July 13th, 1943, she took a torpedo at the bow with, amazingly, no loss of life. Temporary repairs were enacted to keep her afloat and viable for subsequent operations. On June 15th, 1944, her guns were used in anger against enemy positions at Saipan. An aerial attack by Japanese "Val" dive bombers on January 14th resulted in twenty-three dead and twenty wounded. A month of repairs then followed. In November of 1944, she was the victim of a successful Kamikaze attack (some 12 to 14 enemy warplanes taking part) resulting in multiple fatalities. The on-the-spot bravery and thinking of her crew kept fires from gaining control of the ship. The end of the war in the Pacific arrived on August 15th, 1945 with USS St. Louis now a battered, but surviving, veteran - having earned 11 Battle Stars for her service in the conflict which took her from Bougainville, the Mariana Islands, Leyte and Okinawa.
She remained on station in Asian waters during the immediate post-war period, undertaking minesweeping operations in the East China Sea, and served as part of Operation "Magic Carpet", the return of veterans to U.S. soil, in some of her final actions. She was deactivated on February 25th, 1946 and decommissioned on June 20th of that year. On January 22nd, 1951, she was officially struck from the Naval Register and given over to the Brazilian Navy where she served out the rest of her days as Almirante Tamandare (C-12). She held the post of flagship of the fleet until 1976 before being decommissioned for second time and placed in reserve. Her stripped hulk was then sold for scrap to Taiwan in 1980. However, the warship took on water and sunk near the Cape of Good Hope (South Africa) en route to the island nation.