TwelveOfTwenty #519: "As we'll see later, many paid for it with their jobs."
Corwin began as Mississippi Democrat Senator Jefferson Davis' proposal in December 1860.
Republicans stood strong against Democrat Davis' proposal and several others -- resulting in Mississippi's secession -- until NY Senator Seward took charge of the Corwin proposal.
Then a minority of Republicans flipped to join unanimous Democrats to pass the Amendment in Congress.
Most historians consider NY Senator Seward at that time to be a "loose cannon", not an instrument of Republican policy.
Regardless, no state "un-seceded" due to Corwin, but two Border states and two Northern states ratified it (Illinois is disputed) and one each later rescinded their ratifications.
The real question here is not Corwin in February 1861 (by then it was too late for the Deep South), but rather Davis' similar proposal in December 1860 -- had Republicans accepted Davis' terms, would he, could he, should he have kept Mississippi & other Deep South states from following South Carolina's lead?
We'll never know, of course, however Davis' proposal by itself makes clear that in December 1860 it was, indeed, all about slavery -- regardless of what Davis himself falsely claimed years later.
As for the fate of those minority RINOs who flipped to support Corwin -- I've not seen that before, will be interested to learn.
Hopefully they'll prove a teachable lesson for today's Cheney's & Kinzingers.