He was the son of an ordinary day laborer and had few early educational advantages, but he was appointed to the Naval Academy and was graduated at the head of his class.

He was on the frigate _Potomac_, with the rank of master, when the war broke out, but was too young to secure a command during the war.

He became a lieutenant in July, 1862, and served with that rank on the practice ship _John Adams_ at the Naval Academy and on the ironclad _Patapsco_.

On January 15, 1865, the _Patapsco_ attempted to force an entrance into the harbor of Charleston, which was one network of mines.

Sampson exposed himself fearlessly and the ship met with a fearful disaster by being blown up by a submarine mine.