USS Semmes (DD-189/AG-24/CG-20) was a Clemson-class destroyer in the United States Navy during World War II. She was the first Navy ship named for Commander Raphael Semmes (1809–1877). Semmes was laid down on 10 June 1918 by the Newport News Shipbuilding & Dry Dock Company, Newport News, Virginia; launched on 21 December 1918; sponsored by Mrs. John H. Watkins, granddaughter of Raphael Semmes; and commissioned on 21 February 1920, Commander H.H. Norton in command. Following shakedown, Semmes participated in exercises along the northeast coast until January 1921 when she sailed south for winter fleet maneuvers in the Caribbean. From there, she transited the Panama Canal to cruise off the west coast of South America and returned to the Caribbean in late February to conduct further exercises out of Guantanamo Bay. In late April, she resumed operations out of Norfolk, Virginia. The destroyer was ordered inactivated in 1922; and, on 12 April, entered the Philadelphia Navy Yard where she was decommissioned on 17 July. Activated ten years later, she was transferred to the United States Coast Guard to serve in the Rum Patrol. She was commissioned in that service on 25 April 1932. As a Coast Guard destroyer, she was reconditioned at Boston, Massachusetts and based at New London, Connecticut whence she operated from 25 September until detached for two months duty with the Navy on 7 September 1933. On 10 November, she returned to New London and resumed operations for the Treasury Department. On 20 April 1934, the destroyer was returned to the Navy and was recommissioned as an experimental ship in accordance with the London Treaty limiting naval armament. Although not officially redesignated as an auxiliary ship, AG-24, until 1 July 1935, Semmes was assigned to Experimental Division 1: and, with assigned submarines, tested and evaluated underwater sound equipment into the 1940s. After the entry of the United States into World War II, Semmes added escort missions, training services for the Key West Sound School, and antisubmarine patrol work to her duties. At Key West from 16 March to 16 April 1942, she performed escort and patrol work off the mid-Atlantic seaboard into May; and, on the morning of the 6th, while patrolling off Cape Lookout, collided with a British ship, Senateur Duhamel. The latter sank; and, after assisting the survivors, Semmes put into Morehead City, N.C. for temporary repairs. Permanent repairs were completed at Norfolk on 3 June and the former destroyer resumed her test and evaluation, patrol, and escort work which she continued through the end of the war in Europe. After the capitulation of Germany, Semmes resumed her primary mission of testing experimental equipment and, for the remainder of her career, conducted tests for the Underwater Sound Laboratory, New London, as a unit of the antisubmarine surface group of the Operational Development Force. Other duties during that period included the provision of training services to the Submarine School and to the Fleet Sonar School. On 21 May 1946, Semmes again entered the Philadelphia Navy Yard for inactivation. Decommissioned on 2 June 1946, her name was struck from the Navy list on 3 July 1946; and her hulk was sold for scrapping to the Northern Metals Corporation, Philadelphia, Pennsylvania on 25 November 1946. She was scrapped the following year. Semmes received five battle stars for service in World War II.