Born April 4, 1792, in Danville, Vermont, to a poor family, Thaddeus Stevens grew up on what was then still the edge of the wilderness. His father abandoned the family when Stevens was just a boy. Stevens owed most of his future success to the virtues of industry and hard work instilled in him by his mother. Educated at Dartmouth College, Stevens became a schoolteacher in York, Pennsylvania. He went on to study law at the University of Vermont, as well as in Maryland, and became a lawyer, opening his practice in Gettysburg, Pennsylvania, in 1816.

Stevens was at first only a moderately successful lawyer. However, after defending a murderer on the grounds of insanity —an early example of the use of this plea—he suddenly became well known. Stevens was called in on most of the important cases in his area, and he argued cases before...