|Launched:||23 May 1941|
|Commissioned:||3 July 1941|
|Reclassified:||AGC-18, 10 October 1944|
|Decommissioned:||29 June 1946|
|Fate:||Transferred to the U.S. Coast Guard, 19 July 1946.|
|Length:||310 ft 9 in|
|Beam:||41 ft 1 in|
|Draft:||13 ft 6 in|
|Armament:||two x 5 inch guns|
Following her shakedown cruise, USS Biscayne joined the Atlantic Fleet and operated out of Boston, Massachusetts, on patrol and plane guard missions 7 December 1941-27 May 1942. For the next four months she served as a seaplane tender and communications ship in Newfoundland and Greenland waters.
The tender departed Norfolk, Virginia, 17 October 1942 and after a short stop at Guantanamo Bay, Cuba, moved to Freetown, Sierra Leone, with Patrol Squadron 92, arriving 2 November 1942. She moved to Casablanca, French Morocco, on 18 November and remained there until 25 April 1943 supporting patrol squadrons.
USS Biscayne arrived at Mers-el-Kebir, Algeria, 26 April 1943 and became the flagship of Rear Admiral Richard Lansing Conolly, Commander, Landing Craft and Bases, Northwest African Waters. While at Mers-el-Kebir she was fitted out as an amphibious force flagship by , 2-31 May 1943. She was not reclassified AGC-18 until 10 October 1944. In May she shifted her moorings to Bizerte, Tunisia. Departing 10 July 1943, she served as flagship of the Joss (Licata) Force in the invasion of Sicily. USS Biscayne remained off Sicily until 22 July and then returned to Bizerte.
During 9 September-11 October 1943 USS Biscayne took part in the landings at Salerno, Italy, as flagship for Admiral Conolly and Vice Admiral H. K. Hewitt. While off Salerno, she escaped unscathed from frequent air and gunfire attacks. On 12 September she sent a fire and rescue team on board the British ammunition ship Lyninge and saved that vessel and her cargo of ammunition from destruction. USS Biscayne also served as a temporary hospital ship while off Salerno.
USS Biscayne retired to Bizerte 11 October 1943 and on 7 November 1943 became the flagship of Rear Admiral F. J. Lowry, Commander, 8th Amphibious Force. Sailing for Italy once again, she served as flagship during the Anzio landings (22 January-2 February 1944). She became flagship of Rear Admiral B. J. Rodgers, Commander, Amphibious Group 2, 8th Amphibious Force, in May 1944 and during 15 August-16 September 1944 took part in the invasion of southern France.
USS Biscayne left the Mediterranean on 12 October 1944 for Boston, and then steamed to the Pacific. She arrived at Pearl Harbor 9 January 1945 and became flagship of Frederick Moosbrugger, Commander, Destroyer Squadron 63. She took part in the invasion of Iwo Jima (19 February–4 March 1945) as flagship of the transport screen. USS Biscayne carried out similar duties during the landings on Kerama Retto, Okinawa (26 March-1 April) and on Okinawa itself. She remained off Okinawa until 1 July 1945, during which time she served as flagship for the occupation of Iheya and Aguni Islands, Okinawa (3-9 June). After her tour at Okinawa, USS Biscayne retired to Leyte and remained in the Philippines until departing for the occupation of Korea 8 September. She remained on occupation duty in Korean and Chinese waters until 30 October when she left for the United States.
USS Biscayne arrived at San Diego, California on 21 December 1945 and Portland, Maine on 7 January 1946. She then moved to the U.S. Naval Academy for use as quarters for the aviation instruction staff.