If the loser confederates had accepted the overtures of Lincoln to stay he would have rewarded them with ratification of the Corwin amendment. There is evidence that he may have co wrote it. If the losers had simply obeyed...slavery would have never been abolished.
"No amendment shall be made to the Constitution which will authorize or give to Congress the power to abolish or interfere, within any State, with the domestic institutions thereof, including that of persons held to labor or service by the laws of said State."