[1] After a shakedown cruise in the Gulf of Paria, between Trinidad and Venezuela, the new heavy cruiser was assigned, 27 March 1944, to Task Force 22 and trained in Casco Bay, Maine, until she steamed to Belfast, Northern Ireland, with TG 27.10, arriving 14 May and reporting to Commander, 12th Fleet for duty.

General Dwight D. Eisenhower, Supreme Commander, Allied Expeditionary Force, accompanied by Rear Admiral Alan G. Kirk, inspected the ship's company in Belfast Lough 15 May 1944.

Nineteen of the twenty-one primary targets assigned the task force were successfully neutralized or destroyed thus enabling Army troops to occupy the city on 26 June.

President Franklin D. Roosevelt and his party embarked on Quincy on 23 January 1945, at Newport News, Virginia, for passage to Malta, arriving 2 February.

After receiving calls by British Prime Minister Winston Churchill and other dignitaries, President Roosevelt departed Quincy and continued on to the Crimea by air to attend the Yalta Conference.

USS Quincy departed Malta 6 February 1945, and arrived at the Great Bitter Lake in the Suez Canal two days later, after calling at Ismalia, Egypt.

The President and his party returned to Quincy on 12 February, following the Yalta Conference with Soviet leader Josef Stalin and Churchill, and the next day received King Farouk of Egypt and Haile Selassie, Emperor of Ethiopia.

From 14 February, President Roosevelt and King Abdul Aziz of Saudi Arabia, known in the West as Ibn Saud, met aboard Quincy.

[4][5][6][7] After a call at Alexandria, and a final meeting between President Roosevelt and Prime Minister Churchill, Quincy steamed for Algiers, arriving on 18 February.

[8] Following a presidential conference with the American ambassadors to Great Britain, France and Italy, the cruiser steamed for the United States, arriving at Newport News on 27 February.

The cruiser departed Leyte 1 July with Task Force 38 to begin a period of strikes at Japan's home islands which lasted until the termination of hostilities on V-J Day.

Quincy joined the Support Force, 23 August, and four days later, helped occupy Sagami Wan, Japan, and entered Tokyo Bay 1 September.

Following fitting out and readiness training, she served in the screen of the Fast Carrier Task groups ranging off the coastline of Korea from 25 July 1953 to 1 December 1953.