A Lieutenant Colonel in the Mexican War, Black eventually served as Governor of the Nebraska Territory. In 1861, he resigned his governorship, believing so strongly in the Union cause that he was willing to fight and die to defend it. After achieving the rank of Colonel, he was killed in the Battle of Gaines Mill, Virginia, on June 27, 1862 at age 45. He left behind a wife and only son. His mortal remains were buried in Allegheny Cemetery July 21, 1866. Colonel Black's memorial reads "Dulce et decorum est pro patria mori," latin for "sweet and right it is to die for one's country."