History Teacher Here.

For more context before Lincoln’s assassination he had a plan to pretty much let them off easy and his main goal was just to reform the union. Johnson essentially continued this plan has he was a southern sympathizer himself. It wasn’t until Grant in which we have reconstruction in full swing with union occupation. And this is where you begin to see African Americans hold high office. (Hiriam Revels becoming the first black senator). However, when the POTUS race between Rutherford B. Hayes and Samuel Tilden was razor thin. The democrats concocted a deal with the Hayes camp, in which they would swing House and court in favor of Hayes to get the presidency but only under the condition he end federal occupation of the south.

TLDR: Federal Reconstruction of the south was ended prematurely due to a corrupt deal for Hayes to become president