A railroad construction engineer by background, he was selected by the Confederate government to build two forts to defend the Tennessee and Cumberland rivers. The location of Fort Henry on the Tennessee was vulnerable to flooding, but Tilghman was slow to spot this, and his surrender of the fort to U.S. Grant in February 1862 was regarded as a disgrace. Taken prisoner and exchanged, he commanded a brigade in the Vicksburg campaign, and was killed by a shell at the Battle of Champion Hill, where he was widely praised for gallantry.