Some of the challenges facing blacks after the war were pretty bad. I mean A: they did get saved from slavery so thats a change for the better. But in the south, segregation was enforced. A LOT. Blacks had to use MARKED areas instead of joining the whites. Blacks were blamed a lot by southern citizens for causing trouble. Blacks also had to deal with lynching (Basically hanging) from southern citizens (Mostly from the KKK). Mostly what the federal goverment did was creating a bureau named the "Freedmen's Bureau". Which its goal was to provide assistance to former slaves (Freedmen).
Explanation: Independence, see List of incidents of civil unrest in Colonial North America. Wikipedia has articles on most of the major episodes of civil unrest.