Rear Admiral John Adolphus Bernard Dahlgren is known as the 'father of American naval ordnance.' Dahlgren was assigned to the Washington Navy Yard in 1847 as an ordnance expert, and served there until 1863. As commander of the yard, he would establish the Bureau of Ordnance. Dahlgren is most famous for his small boat howitzer design as well as his design of the cast-iron muzzle loading shell gun known as the Dahlgren gun. Named commandeer of the South Atlantic Blockading Squadron, he maintained the blockade of Savannah and Charleston until those ports were captured by land forces commanded by William T. Sherman.