Answer:
Black Codes (to get around the amendment) and protests
Explanation
Congress passed the 13th Amendment to the Constitution, outlawing slavery, before the Civil War had ended. Once the war was over, white southerners passed laws (known as Black Codes) to keep freedmen from exercising their rights, and Congress responded by passing a Civil Rights Act in 1866 to ensure black citizenship. Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.