One man did more to shape Reconstruction than any other: President Andrew Johnson, who so infuriated Congressional Republicans that they went much farther than they might otherwise have done. He was "headstrong, domineering," noted one congressman, "having fought his way in a state [Tennessee] filled with aristocratic Southerners from the class of so-called 'low whites' to the highest position in the United States. . . . He sought rather than avoided a fight." Johnson despised secessionists, but he was violently racist. After succeeding the assassinated Lincoln, he swiftly took measures to guarantee white supremacy in the old Confederacy.

This 1866 cartoon by Thomas Nast captures the Northern backlash against Johnson's actions. Depicted here as Iago, scheming for evil in the South, Johnson accepted the "black codes," laws that virtually reenslaved African Americans; he also tolerated the widespread violence against freed slaves that culminated in bloody white riots in Memphis and New Orleans. Even racist Yankees bridled against this treatment of African Americans, who had had been loyal to the Union during the Civil War and had supplied tens of thousands of troops for the cause. Johnson vetoed Congress's initial, limited measures to aid blacks and extend civil rights, and so radicalized even moderate Republicans.