Henry Gantt, son of Dr. John W. Gantt and Sarah Blakey Gantt (née Perkins), was born in Virginia in 1831. He attended the Virginia Military Institute from 1848 to 1851; graduating as 23rd out of 29. Farming and managing one of his family possessions, 508 acres of land named Valmont, he inherited that land when his father died in 1860. In the wake of John Brown's raid in 1859 Henry Gantt joined the Virginia Militia, by 1861 being captain and commanding officer of the Scottsville Guard.