After the Civil War, #Black people had begun gaining political power due to Reconstruction and amendments giving them the right to vote. They registered en masse and, in the 1874 election in Mississippi, swept Republicans into the governor’s office and the legislature.

Southern Whites still plotted to keep Black people from registering and voting, however. Their tactics were called the Mississippi Plan. White paramilitary organizations like the Red Shirts openly attacked and murdered Black people and caused riots at Republican rallies. White planters and landlords also got involved to intimidate Black sharecroppers who dared to vote. The Republican governor asked for help from the federal government and was refused. By the next election, Black voter turnout was nearly nonexistent in Mississippi, and the tactic had spread to other Southern states.

In 1877, a disputed election led to a compromise between the northern Republicans (the party of Lincoln) and the southern Democrats that subsequently meant the federal government would do little to enforce 14th and 15th amendments. Reconstruction was over.

Source: http://voyager.dvc.edu/~mpowell/afam/creating2.pdf