Although it might seem like states can do anything they want there is limits on what they may do. The Constitution could not address any scenario that might have developed. The Founders made concessions as to slavery hoping that it would eventually die on the vine. The South was not willing to just keep what they had because Lincoln and the Republicans did offer concessions to them. They refused. They wanted to expand slavery to the new territories. No matter what the arguments about whether it was proper to fight the war the issue will forever remain the same. Slavery was wrong and will forever be wrong. Enslaving your fellow man is against those "Inalienable Rights". Those Rights don't just apply to certain people. They apply to all people.

One would hope that you people that are so passionate about States Rights and The Constitution would at least apply that thinking to current events. You apparently have no problems for State AG's and Governors usurping election law from their Legislatures in the last election in order to steal it. So far there has been no wailing and gnashing of teeth about Pence and McConnell allowing Biden to be confirmed illegally but you sure can find ways to defame the only president in history that had the fortitude to address our greatest national disgrace.
The war was prosecuted whether we like it or not and the issue has been decided. Reliving old grievances only creates turmoil again. Instead of opining about what we think should or might have taken place and dead people's motives we would do well to just take a hard look at History. What did happen. We know what happened at Gettysburg but trying to get into the heads of the participants is a mistake. Let our honored dead rest in peace. Embrace each other as fellow Americans instead of territorial enemies. One of Trump's greatest achievements in office was to bring people of all colors and nationalities together. He did more for black Americans than any other president since Lincoln.