(DE-684: dp. 1,450, 1. 306'; b. 37', dr. 9'8" s. 24 k.; cpl. 186; a. 2 5", 3 21" tt., 8 dcp., 1 dcp. (Lh.), 2 dct.; cl. Rudderow)
The third DeLong (DE-684) was launched 23 November 1943 by Bethlehem Steel Co., Quincy, Mass.sponsored by Mrs. L. C. DeLong, mother of the late Corporal DeLong, USMCR; and commissioned 31 December 1943, Lieutenant Commander R. C. Houston in command.
DeLong arrived at Miami 10 March 1944 for training duty off Florida until the end of the war. On 16 August 1945 she was reclassified APD 137 and sailed to Charleston, S.C., for conversion to a high speed transport. She arrived at St. John's River, Fla., 6 November, and was placed out of commission in reserve there 25 April 1947.
With the outbreak of the Korean War, DeLong was recommissioned 7 February 1951 and joined in hunterkiller exercises in the North Atlantic, visiting Nova Scotia. She served as training ship at the Fleet Sonar School at Key West from 4 April to 11 July 1952.
DeLong sailed from Norfolk 26 August 1952 to participate in Operation "Mainbrace," the first NATO exercise to consolidate the operations of the navies of seven countries. After visiting Edinburgh, Scotland, and Arendal, Norway, and escorting transports to an amphibious exercise on the Danish coast, she returned to Norfolk 11 October. She reported to Key West again 5 January 1953, for service with the Sonar School. In summer 1953 she made a midshipman cruise to Santos, Brazil, and Widespread, Curacao and the next summer she took part in a midshipman cruise to Dublin, Ireland, and Portsmouth, England. DeLong continued to alternate periods of service at the Sonar School at Key West with local operations at Norfolk and overhauls at Charleston. She also joined in large scale exercises in the Caribbean.
On 2 January 1958 DeLong cleared Norfolk for New York, arriving the next day. Through 1962 she served as reserve training ship for the 3d Naval District, cruising Long Island Sound, and occasionally to Puerto Rico.