Klan War: Ulysses S. Grant and the Battle to Save Reconstruction, by F. Bordewich

The South never fully surrendered, just turned to guerilla warfare with the brutal terror tactics of Ku Klux Klan. The terrible luck of having VP Andrew Johnson take over as President after Lincoln was assassinated allowed an infection of white grievance and victimhood to gain a foothold and flourish in the South. Freed blacks and their white allies were threatened, driven to flee, tortured, killed with impunity by powerful, armed southern enemies of Reconstruction.
President Grant was a decent, humane man who worked to suppress and destroy the Ku Klux Klan, but ultimately he lost the political backing needed to finish the job. "Had Grant's campaign been properly financed, sustained over time, and supported by consistent punishment by the courts it could have not only destroyed the Klan but ensured the survival of a two-party system and civil rights in the South. In the end, lasting change required more than white America was prepared to give.
Personally, it was hard finish reading this--kept thinking about quiet, pretty little Southern towns I've visited or driven through--where hideous torture, mutilations and murders went unpunished, and freed people and white allies were subjected to grinding years of intimidation and terror. The damage of the failure of Reconstruction continues. Teaching false mythology about US history must not continue.