If Britain had offered after Bunker Hill to repeal all the taxes they'd imposed on the colonies -- or decided after the Declaration of Independence was adopted that they'd never impose another tax on Americans -- the colonists would have rejected their offer.
That rejection wouldn't mean that "taxation without representation" wasn't the main issue and the cause of the war. It was just that too much had happened. It wasn't enough anymore for Britain to back down. The Colonists wanted out of the empire completely.
So it was with the Corwin Amendment. If it had been adopted in 1850, Southerners might have been happy with it. It wouldn't have been adopted then -- it was only as a last ditch attempt to save the Union that Northerners considered it -- but by 1861 it was too little too late.
I could site other examples of "too little too late" -- if the Germans or Japanese had decided after Normandy or Iwo Jima that they'd leave the countries they'd conquered and retreat behind their earlier borders in exchange for peace, the Allies wouldn't have accepted their offer, even though Axis conquest of those territories had been the reason the Allies had fought against them -- but the point isn't that hard to grasp.
You might say that rejection of the Corwin Amendment meant that Southerners who were active in politics thought something else more important than slavery. Someone else would respond that at the time they (wrongly) felt that slavery would be most secure outside the union rather than inside. It's possible that independence had become more important for secessionists than slavery at that particular moment, but what had motivated them up until that point? What was behind the movement? Slavery is a very good answer to those questions.
The funny thing in all this is that people who wouldn't trust a "Yankee" any further than they could throw him, people who always assume that Lincoln had something up his sleeve, also assume that the secessionists took Northerners at their word and rejected a good faith offer by the government to ensure slavery's survival in the South. If you trust Northerners so little, and the secessionists of 1861 trusted them so little, maybe they didn't respond to the Corwin Amendment because they knew (or suspected) that Northerners weren't on the up-and-up, and wouldn't honor it.
Just as the Southern states wanted out of the empire completely. Empire.
...but the point isn't that hard to grasp.
You've done a great job making your point:)
You might say that rejection of the Corwin Amendment meant that Southerners who were active in politics thought something else more important than slavery. Someone else would respond that at the time they (wrongly) felt that slavery would be most secure outside the union rather than inside. It's possible that independence had become more important for secessionists than slavery at that particular moment, but what had motivated them up until that point? What was behind the movement? Slavery is a very good answer to those questions.
Slavery is a very good answer. But, it's incomplete. "Internal improvements" were a continual rub to those same Southerners and that brings us to the tariffs. When you include all of these things the picture becomes more complete. If slavery had been the sole motivation for the Southern states, they probably would have accepted the Corwin Amendment and moved on with their lives.
If you trust Northerners so little, and the secessionists of 1861 trusted them so little, maybe they didn't respond to the Corwin Amendment because they knew (or suspected) that Northerners weren't on the up-and-up, and wouldn't honor it.
Well, that's certainly one way to look at it, but I believe you had it right earlier in your post - it was simply too little, too late.