Admiral Dahlgren and officers on deck of Pawnee. John Adolphus Bernard Dahlgren (November 13, 1809 - July 12, 1870) was a United States Navy officer. In the American Civil War, Dahlgren was made commander of the Washington Navy Yard, where he established the Bureau of Ordnance. In 1863, he took command of the South Atlantic Blockading Squadron at the rank of rear admiral