Confederates weren’t just vicious racists and traitors, they were also losers. They lost a single election and quit the country, then lost the war and pretended to surrender so they could try terrorism instead. Losers and cowards.
Oh and they also conspired to assassinate the president, Secretary of State, Grant, and the Secretary of War. Succeeded by shooting Lincoln in the back of the head. Stabbed Seward while he slept and was injured already. Scurried away from Stanton. Chickened out on Grant.
Their campaign of terror included assassinating thousands of freed blacks who they worked assiduously to disarm. The KKK was a gun control group. Again, because they were afraid to fight fair; they preferred their enemies unarmed.
Through a campaign of violence & voter intimidation, which included many, many murders of black & white elected officials, they made it costly to continue keeping federal troops in the south. When the Panic if 1873 was met with austerity, it plunged the country into a depression
Democrats swept the 74 midterms and 2 years later the presidential election was deadlocked and Democrats gave it to Republicans in exchange for ending Reconstruction. Now with troops gone, those chickenshit cowards could unleash even more violence on the black population
“All the Powers of Earth” by Blumenthal is a good place to start on the politics. Grant’s memoir is great and the Chernow bio of him is good. “Stanton” goes into a good amount of this from the War Secretary position. DuBois and Foner on Reconstruction.
Others probably have better suggestions so folks should post them here
And this fact should be taught to every student: The people who ended slavery were the former slaves themselves, who forced a political crisis by so frequently risking everything to escape. From my own book We’ve Got People: 
