Dahlgren. I. John Adolf, an American naval officer, born in Philadelphia in November, 1809, died in Washington, July 12, 1870. He was appointed midshipman in 1826. His first cruise (1827-'9) was in the frigate Macedonian of the Brazil squadron. He next served (1830-'32) on the sloop Ontario of the Mediterranean squadron. From 1836 to 1842 . he was employed on the coast survey, and he received a commission as lieutenant in 1837. In 1844-'5 he served on the frigate Cumberland of the Mediterranean squadron. From 1847 to 1857 he was employed in the ordnance department, and made a series of experiments in the construction of heavy shell guns, which resulted in the adoption of a new pattern, called the Dahlgren gun. He also invented a rifled cannon for naval warfare, and introduced into use bronze howitzers of 12 and 24 pounds calibre. He published "Report on the 32-pounders of 32 cwt." (1850), "System of Boat Armament in the United States Navy" (1852), "Naval Percussion Locks and Primers" (1852), and "Shells and Shell Guns" (1856). He received a commission as commander in 1855, was in command of the ordnance ship Plymouth in 1858-9, and in 1860-'61 was engaged in ordnance duty at the Washington navy yard, to the command of which he was assigned in 1861. He was promoted to the rank of captain in July, 1862, and was shortly afterward appointed chief of the bureau of ordnance.
Having been appointed rear admiral, Feb. 7, 1863, he was placed in command of the South Atlantic squadron. From 1866 to 1868 he was in command of the South Pacific squadron. In 1869 he resumed command of the Washington navy yard. II. Ulric, son of the preceding, an American soldier, born in Bucks co., Pa., April 3, 1842, killed near King and Queen's Court House, Va., March 4, 1864. When the civil war broke out he gave up the study of the law, and assisted his father in the ordnance department. He afterward entered the army, and performed distinguished service. Shortly after the battle of Gettysburg he headed a cavalry charge into Hagers-town, where he lost a leg. He was promoted to the rank of colonel, and having recovered from his wound, engaged in a cavalry raid, the object of which was the liberation of the Union soldiers confined in Libby prison and at Belle Isle, in Richmond. Upon this expedition he fell into an ambush and was killed. A memoir of him was written by his father, and revised and republished by his stepmother (Philadelphia, 1872).