Hans L. Trefousse, "Johnson, Andrew," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00566.html.
The election of Abraham Lincoln and the subsequent secession crisis confronted Johnson with a difficult choice. Should he, like other Tennessee Democrats, uphold southern pretentions, or should he declare his Unionism, a position more popular among the opposition in East Tennessee than among his own party associates? Johnson never hesitated; fully convinced that the Union must be preserved and knowing that there would be no future for him in a southern Confederacy dominated by men like Jefferson Davis, whom he had fought for years, he defied the southern mainstream. After introducing constitutional amendments calling for the direct election of presidents, limitation of the terms of Supreme Court justices, and the division of the remaining territories between free and slave states, on 18-19 December 1860, in a ringing Senate speech in support of these amendments, he called secession treason and demanded that the government enforce the Constitution and the laws. Although he never said that states could be coerced--he wanted individuals to be held to their obedience--he was denounced as a traitor throughout the South. But in the North he became a hero, and his reputation was not diminished by two more antisecession speeches on 5-6 February and 2 March 1861.