Charleston Harbor, S.C. Rear Admiral Dahlgren standing by a Dahlgren gun on deck of USS Pawnee, circa 1863-65. John Adolphus Bernard Dahlgren (November 13, 1809 - July 12, 1870) was a United States Naval Officer. He was assigned to the Washington Navy Yard in 1847 where he established the U.S. Navy's Ordnance Department where he became an ordnance expert, developed a percussion lock, and wrote a number of books. Under his command, the Navy established its own foundry, and its first product was the Boat Howitzer, which was designed to be used on both ship and in landings. But it is his cast iron muzzle loading cannon which came to bear his name (the Dahlgren gun) and be his most famous contribution. In 1862, Dahlgren was promoted to the rank of captain and made chief of the Bureau of Ordnance. In 1863 he was promoted to Rear Admiral and took command of the South Atlantic Blockading Squadron. In 1864, he helped William Tecumseh Sherman secure Savannah, Georgia. After the Civil War he took command of the South Pacific Squadron from Rear Admiral George F. Pearson, in 1867. When he was relieved of the command of the Squadron in 1869, he returned to the Washington Navy Yard where he served until his death in 1870 at the age of 60.