Dahlgren, John (Adolphus Bernard) (1809–1870)

US naval officer and inventor. He joined the navy in 1826. From 1847 on, he experimented with naval weaponry design. He became a rear admiral and was commandant of the Washington Navy Yard at his death.

Born in Philadelphia, he was classically educated. When he first joined the navy as a midshipman, he served in the Mediterranean, later becoming an assistant in the US Coast Survey. It was as ordnance officer at the Washington Navy Yard that Dahlgren started to take an interest in improving weapon design and, by 1851, the yard had begun to produce a cannon to his specifications. During his time as a rear admiral, he commanded the Union's South Atlantic Blockadina Squadron (1863–65).