One was a robust charmer given to fits of passion, whose physical appeal could captivate women as easily as cajole colleagues. The other was a frail, melancholy man of quiet intellect, whose ailments drove him eventually to alcohol and drug addiction. Born into different social classes, they were as opposite as men could be. Yet these sons of Georgia, Robert Toombs and Alexander H. Stephens, became fast friends and together changed the course of the...