Outstanding post.
I wonder if Lincoln had had the wisdom to foresee the eventual terrible human costs and deprivation of the Civil War would he have still pursued it? At some point the costs of the war became self-evident. Perhaps there may have been an opportunity for a truce between the two sides before things got out of hand.
Instead of pulling a lanyard on an artillery piece, maybe South Carolina should have sued in Federal Court for their secession. I would expect the Taney Supreme Court would have declared their right to secession as Constitutional.