DAHLGREN, drd'gren, JOHN ADOLF (1809 :0). An American naval officer, prominent on the Federal side during the Civil War. He was born in Philadelphia of Swedish parentage; en tered the United States Navy as a midshipman in 1826; cruised for a time on the Macedonian and the Ontario; and from 1834 to 1838 was en gaged in the United States Coast Survey work, for which his aptitude and training in math ematical studies had well fitted him. In 1S37 he was promoted to the rank of lieutenant, but in the same year was forced by failing eyesight to leave the active service, and did not resume his duties until 1842. After a cruise of two years in the Mediterranean on board the Cum be•land, be was assigned to the Ordnance De partment, which absorbed the greater part of his energies from this time on, and of which he was twice chief—in 1862-63 and in 1868-70. In his many years of service be greatly increased the efficiency of the department and became espe cially well known through his invention (1850) of the Dahlgren gun, which proved of the utmost value to the Government during the Civil War. In April, 1861, on the defection of Franklin Buchanan (q.v.), he succeeded that officer as commandant of the Washington Navy Yard, a po-. sition which he held until the fall of 1862, when he became chief of the Bureau of Ordnance. In February, 1863, he was raised to the rank of rear admiral, and in July replaced Admiral Dupont as commander-]n-chief of the South Atlantic blockading squadron, the greater part of which was engaged in the siege of Charleston, S. C.
Soon after taking command, he, in cooperation with General Gillmore, the commander of the Federal troops near Charleston, succeeded in capturing Morris Island, silencing Fort Sumter, and completing the closing of the port. Finally, in February, 1865, Charleston was evacuated by the Confederates, and Dahlgren occupied Charleston Harbor, while General Schimmelpfennig took pos session of the city. Soon afterwards he resigned as commander of the South Atlantic squadron, and from 1866 to 1868 commanded the South Pacific squadron. After finishing his second term as chief of the Bureau of Ordnance, he was placed in command, at his own request. of the United States Navy Yard in Washington, where several months later he died. In addition to many reports and magazine articles, he published Thirty-two-Pound Practice for Ranges (1850); Systems of Boat .1 moment in the United States Nary (1852) ; Karat Percussion Loch's and Primers (1852) ; Ordnance Memoranda (1853) ; Shell and Shell Guns (1856) ; and an uncom pleted volume entitled Notes on Maritime and Int,inational Law was published posthumously in 1877. Consult Madeleine V. Dahlgren (his widow), Memoir of John A. Dah(yaw (Boston, 1882).