It was clearly not silly because Lincoln didn't think it was silly.
Did it work?
It was clearly insufficient to convince the seceded states that they should remain in the Union.
Apparently they either believed it wouldn't happen, it wouldn't be effective, or it simply wasn't what they really wanted.
Considering direct trade with Europe would have moved 200 Million dollars per year in trade out of the hands of New York and Washington DC and into their own hands, I'm suspecting that this was what they were really after.
Always follow the money.
Thank you, Captain Obvious. The Corwin Amendment did not mandate slavery in new territories, the Confederate constitution did. The Corwin Amendment did not prevent states from completely barring slavery within their borders, the Confederate constitution did. Why would the Southern states want to go back to the limited protections of the Corwin amendment when they wrote much greater levels of protection in their own constitution?
Considering direct trade with Europe would have moved 200 Million dollars per year in trade out of the hands of New York and Washington DC and into their own hands, I'm suspecting that this was what they were really after.
Then why didn't the Southern states propose something dealing with that if they were so eager to rejoin the Union as you would have us believe? The obvious answer, obvious to all but you, is that $200 million figure is a figment of your imagination.