The Corwin Amendment was an unratified amendment to the United States Constitution proposed by Representative Thomas Corwin of Ohio in 1861, as a last-ditch effort to prevent the American Civil War. It would have prohibited the federal government from ever abolishing slavery.
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.
The Corwin Amendment represented almost the only proposition every political faction would agree on: Congress should not unilaterally abolish slavery. Outgoing President Buchanan endorsed this amendment, as did President Lincoln in his inaugural address:
I understand a proposed amendment to the Constitution--which amendment, however, I have not seen--has passed Congress, to the effect that the Federal Government shall never interfere with the domestic institutions of the States, including that of persons held to service. To avoid misconstruction of what I have said, I depart from my purpose not to speak of particular amendments so far as to say that, holding such a provision to now be implied Constitutional law, I have no objection to its being made express and irrevocable.
However, by the time Representative Corwin proposed this amendment, the South had already seceded and organized the Confederate States of America. Even if the northern states would have ratified his amendment, it would probably not have been a sufficient condition for peace. Only two states ever ratified this amendment.
While technically still open for ratification, no state has ratified it since the Civil War ended. Since Corwin continued the then-current constitutional policy of never referring to slavery by name, adopting the amendment would definitely not re-establish slavery. However, it could potentially prevent the Federal government from legislating in many local matters.