USS Saint Louis, first of a class of two 10,000-ton light cruisers, was built at Newport News, Virginia. Commissioned in May 1939, she was employed on the Neutrality Patrol and related duties in the Atlantic and West Indies from October 1939 until November 1940, when she was transferred to the Pacific. During the next year, St. Louis served along the west coast, in Hawaiian waters and further west, including one voyage to the Philippines in mid-1941. She was in Pearl Harbor when the Japanese surprise attack on the fleet there began the Pacific War. Her activities during the war's first six months mainly involved escorting convoys between the west coast and Hawaii, plus two trips to the south Pacific and one to Midway island.

At the end of May 1942, St. Louis steamed to Alaskan waters, her zone of operations until the following October. On 7 August she shelled Kiska Island, which had been captured by the Japanese in June. Near the end of 1942, the cruiser went to the south Pacific, where she participated in the final stages of the Guadalcanal campaign and the first part of the offensive into the Central Solomons, conducting bombardments of enemy bases and patrolling to stop his reinforcement efforts. On 6 July 1943, she engaged Japanese warships in the Battle of Kula Gulf. In another such night action, the Battle of Kolombangara on 13 July, she was torpedoed in the bow, necessitating a trip to California for repairs.

St. Louis returned to the south Pacific in November 1943 and soon was at work supporting the Bougainville campaign. She remained active in the area until May and suffered damage when hit by an enemy bomb during the Green Island landing on 14 February 1944. In June, St. Louis moved north to participate in the campaign to seize the Mariana Islands, bombarding Japanese positions ashore on Saipan, and later on Guam. Following another overhaul, she operated off Leyte. On 27 November 1944, she was hit aft by one suicide plane and near-missed by another. The resulting damage was sufficiently severe to require another visit to a west coast shipyard. From March 1945 until the fighting ended in mid-August, St. Louis provided gunfire support for troops ashore on Okinawa and escorted the fast carriers during their attacks on the Japanese home islands and elsewhere in the western Pacific.

For the rest of 1945 and into 1946, St. Louis took part in occupation activities in China and brought U.S. service personnel home as part of Operation "Magic Carpet". She transited the Panama Canal to the Atlantic in February 1946 and was decommissioned at the Philadelphia Navy Yard in June of that year. In January 1951 St. Louis was sold to Brazil. Refitted and renamed Tamandare, she served the Brazilian Navy for more than two more decades. After being sold for scrapping, she sank in the Pacific in August 1980, while being towed to Taiwan.