Freed slaves, and abolished slavery
The thirteenth amendment to the U.S. Constitution abolished slavery and all other forms of involuntary servitude, excluding involuntary labor as punishment for a crime.
"Section 1. 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.
Section 2. Congress shall have power to enforce this article by appropriate legislation."