Let's not and say we didn't.
The, uh..."state's right" in question in 1861 was no less an evil than abortion or starving invalids to death. Slavery is kind of unconstitutional. Once the South seceded, there was no avoiding the remedy that "every drop of blood drawn by the whip would be paid for with a drop drawn by the sword" (I paraphrase.)
I'm from Goldsboro, NC. The South will save this country in the 21st century, but let's face it -- we nearly killed it in the 19th.
The South was willing to listen to reason. It is entirely possible that they would have acceded to an end of slavery the same way it ended in the British West Indies - the gov't declared it illegal & compensated slaveowners for their financial losses.
Regrettable, Northern liberals forced war was upon a proud, noble & independent citizenry.
It led to the destruction of Southern Agriculture, creation of the KKK, thousands of deaths, and an enlarged federal government.
Sorry, but that war was another bit of liberal social engineering run amok. And a war that both President Reagan & President GW Bush would have avoided