Phoenix went on to establish a distinguished combat record in the Pacific, most of her wartime service being with the Seventh Fleet - the naval arm of General Douglas Macarthur's South-West Pacific Forces - commanded by Admiral Thomas Kinkaid. She became the flagship of Task Force 75, built around Phoenix and her sister ships Boise and Nashville and commanded by Rear Admiral Russell S. "Count" Berkey. In April 1944 she led Task Force 75 in providing fire support for the landings at Hollandia in western New Guineau.
In the Leyte operation Phoenix again served as Admiral Berkey's flagship, Berkey this time commanding Task Group 77.3 the Close Covering Group of Seventh Fleet, a task group including Phoenix, Boise and the Australian heavy cruisers Australia and Shropshire.
On October 24 1944 during the Battle for Leyte Gulf Berkey's Task Group was organised as part of Rear Admiral Oldendorf's force preparing to meet the advancing Japanese Southern Force in Surigao Strait, south of Leyte Gulf. The Berkey group was disposed on the right flank of the US disposition, close to the shore of Leyte Island. In the small hours of the next day, during the main gunfire phase of the Battle of Surigao Strait, she was in action against the Japanese flagship Yamashiro, firing her main armament at a rate of four 15-gun salvos per minute. (Phoenix, Boise and Shropshire together fired a total of 1,181 rounds from their main batteries in the seventeen minutes between 0351 and 0408).
From Leyte she went on to support the landings at Mindoro, Lingayen Gulf and Borneo.
After the Second World War she was decommissioned and in 1951 sold to Argentina, becoming a major unit of the Argentinian Navy, and finally acquiring the name Generale Belgrano. In the 1970's she was modernised and equipped with British Seacat short-range missiles, French Exocets and Dutch radar, although she retained her original battery of fifteen 6-inch guns as her main armament.
On 26 April 1982, in the opening stages of the Falklands War between Britain and Argentina, she sortied from the port of Ushaia, escorted by two guided-missile destroyers. On 2 May she was attacked without warning by the British nuclear submarine Conqueror, and hit by two torpedoes. The Belgrano sank rapidly, with the loss of 368 of her crew.
Thus a ship which had participated in the opening drama of the war in the Pacific and survived unscathed, and which at the Battle of Surigao Strait played a role in the last battleship action and the last great surface naval battle in history, became the only cruiser - and the first large warship - to be sunk in action since 1945, and the first ship in history to be sunk in action by a nuclear submarine.