DiogenesLamp: "So is it a gross distortion to say that Lincoln was going to make a deal to keep slavery permanently?"
Yes, because Lincoln believed, like all Americans of his time, that slavery already was permanently part of the Constitution.
So Corwin did not offer a "deal", only reassurances to Border States that Washington, DC, would not attack their "peculiar institution."
Lincoln did not address the constitutionality of making an amendment "irrevocable".
He may well have understood that's impossible -- on logical grounds and was clearly demonstrated when the 18th amendment from 1920 was revoked by the 21st in 1933.
But Corwin's amendment did help reassure Border States like Kentucky & Maryland, and for that I'd guess Lincoln would plead, "guilty as charged".
But Lincoln did in fact attack their "peculiar institution." He weedled and bribed and threatened the various Northern states into going along with his new 13th amendment, and he simply ordered all the legislatures of the Southern states to vote for it or else.
So you see, either way you look at it, Lincoln was lying to someone.
But Corwin's amendment did help reassure Border States like Kentucky & Maryland, and for that I'd guess Lincoln would plead, "guilty as charged".
That, and locking up all the Maryland legislatures that would vote for Independence. The Union army also played a heavy role in suppressing further efforts for states to become independent.
But you are deliberately glossing over the central point, and the Central point is that Lincoln is on record as saying he would support an amendment that would further protect slavery. You attempt to mollify your discontent with this truth by claiming it was a clever tactic to keep the border states, and you do this because you don't want to believe that Lincoln could actually be so unprincipled as to really support such an amendment.
To you, this "tactic" is insincere, which if you think about it is also evidence of Lincoln being unprincipled.
I don't envy you the logical contortions you must go through to square all of the existing facts with what you wish to believe.
I, fortunately have a much easier task. I simply look at the facts, and I make objective conclusions from them.
Lincoln was lying to someone, either before the war or after the war, it doesn't really matter.