The USS Dahlgren (Torpedo Boat No. 9, TB-9, later Coast Torpedo Boat No. 4) was a United States Navy torpedo boat launched on May 29, 1899, by Bath Iron Works in Bath, Maine. She was sponsored by Mrs. J. V. Dahlgren, daughter-in-law of Rear Admiral Dahlgren, and commissioned on June 16, 1900. As an early 20th-century torpedo vessel, Dahlgren was designed for fleet tactics and training, reflecting the evolving naval technology of the period. Constructed for agility and speed, the vessel was primarily assigned to the Atlantic Torpedo Fleet, operating out of Portsmouth, New Hampshire, and Newport, Rhode Island. Her initial role involved developing tactics for her class and training crews in torpedo operations. After an initial period of active service, she was placed out of commission for repairs and modifications in October 1900, returning to partial commission in June 1902. Following further overhaul at Newport, she was fully commissioned again and served as a station ship at New Suffolk, Long Island, until October 1903. Throughout 1905, Dahlgren was assigned to the Naval Training Stations at Newport and New York, supporting training efforts before being placed in reduced commission in December 1905. Subsequently, she was based at Norfolk and later Charleston, South Carolina, where she continued torpedo developmental work. By March 1914, she was placed in ordinary status, indicating a period of reduced activity. In 1917, with the United States' entry into World War I, Dahlgren was fitted for minesweeping and placed in full commission again on April 1. She served primarily on escort duties and harbor entrance patrols at Norfolk until December of that year. Renamed Coast Torpedo Boat No. 4 on August 1, 1918, she continued her service until being decommissioned at Philadelphia Navy Yard in March 1919. The vessel was sold on July 19, 1920. The USS Dahlgren's service reflects the early development of torpedo craft in the U.S. Navy, contributing to tactics, training, and harbor defense during a pivotal period of naval modernization.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.