(DD-187: dp. 1,060; 1. 314'6"; b. 31'9"; dr. 9'4"; s. 36 k.; cpl. 111; a. 4 4", 3 3", 12 21' tt.; cl. Clemson)
The second Dahlgren (DD-187) was launched 20 November 1918 by Newport News Shipbuilding Co., Newport News, Va.; sponsored by Mrs. J. Pierce, daughter of Rear Admiral Dahlgren; and commissioned 6 January 1920, Commander L. Sahm in command.
Dahlgren joined the Atlantic Fleet for exercises and training along the east coast, in Mexican waters, off Guantanamo Bay and in the Canal Zone. She took part in the Presidential Fleet Review at Norfolk in April 1921, and in bombing tests on former German ships off the Virginia coast that summer. On 30 June 1922 she was placed out of commission at Philadelphia.
Recommissioned 26 October 1932, Dahlgren stood out of Norfolk 7 November for San Diego, arriving 30 November. Destroyer operations engaged her along the west coast until April 1934 when fleet exercises brought her to the Atlantic. In January 1936 she returned to San Diego. After a period of similar operations on the west coast, she sailed again for the east on 1 July 1937 and having rescued the crew of a Coast Guard Coast Guard seaplane arrived at New York 21 July 1937.
She served in engineering experiments until 14 June Dahlgren sailed out of Norfolk and Newport on patrols and escorted submarines in their training, and from January to 1 April 1941 she served in the Patuxent River, Md., in experiments in ordnance and submarine detection. Through the summer of 1941 she tested a variable pitch propeller, and subsequently escorted a new cruiser during her trials. On 4 January 1942 Dahlgren arrived at Key West to escort Washington (BB-56) in operations in the Gulf of Mexico. She returned to New York 8 February for a brief period of coastal patrol, and on 24 March sailed to Key West to serve the Fleet Sonar School and carry out patrols. During these operations, she rescued 67 survivors of the torpedoed tanker SS Pennsylvania Sun on 16 July 1942, and nine survivors of the blimp K-74 on 19 July 1943.
On 11 January 1945, Dahlgren arrived at Charleston S.C. to operate with submarines in training until 1 March, when she was reclassified AG-91. She served the Mine Warfare Test Station at Solomons Island Md. until 16 November 1945 when she moored at Philadelphia Navy Yard. There she was decommissioned 14 December 1945, and sold 17 June 1946.