because it was a war that divided the nation. Lincoln knew this and wanted the nation to heal. In some cases families were split. Slavery was an issue, but not the only issue. Had Lincoln (perhaps not goaded the south) there might not be a war...and even then there didn't have to be a war. Had Lincoln stopped building up the troops in Ft Sumpter with the cannons pointed toward Charleston it is very possible the south wouldn't have fired on Ft Sumpter. The south for 3 or 5??? days pleaded for him to not do that, but he did...and perhaps Lincoln thought a war was the only way to keep the union together. MANY of those rangers in Gettysburg and such think that had the South not fired on Ft Sumpter there wouldn't have been a war. Perhaps you recall the north had little interest in a war and little concern that the south wanted out. However, all that changed when the south fired on Ft Sumpter.
I have posted before that in order to sign the constitution, some states would only do so if they were allow to secede and I "think" it was New York that came very close in the war of 1812 or about fifty years before the Civil war and so seceding was not something new. I think we share some sentiments even if our conclusions may be very different. Slavery was wrong, but it was much more common than uncommon in the history of man. All of us had ancestry that were slaves and perhaps slave owners. When looking at history (whether the bible or various events) it is important to put into perspective the mores and norms of the times as well as the verbiage and what it meant at the time. 20th century eyes can see it was very wrong, but perhaps northerners and southerners didn't have those eyes? I believe it was James Adams prodded along by his wife to start addressing the slave market in the 1700s and so there were some with deeper thought than what was common awareness.
Relative to the slave market the north was getting many of the slaves sold by black slave owners in Africa to the slave ships headed for the north to be sold to the south. Tarrifs and tax revenue was going much more to the north than the south and the south depended on agriculture for its money, while there was more industry in the north. Do you think some of that high of 26% that had slaves in the south (not counting the north) were concerned when they had paid money for the slaves while losing more money to the north than the south in taxes to have there slaves released? Again there was more than slavery, but what if the north had been willing to reimburse the south for their money spent? Would there have been a war?
There is small church called Christ's Church (
https://www.historicchristchurch.org/) I've been to 2 or 3 times. Prior to Obama every president has attended at least one service there. Washington and Lee were there as this church is fairly close to Mt Vernon where my first cousin had to correct the officers clothing in Mr Vernon and was very well known there as my second visit to Mt Vernon was with him. He was a military historian that I lost in Covid. Anyway, inside the church are plaques ON THE PEWS where northerners and southerners during Civil War sat in church as well as a half circle pew where previous presidents set. One side would be the south and another side the north. Who were the good guys...who were the bad guys??? Perhaps the war is more complex than people wish to believe. Many wars are like that. That 3/4 of the south population that were not slave owners...any chance with the tax structure and tarrifs that the south viewed the north as overreach and violating states rights much like their ancestry did in the Revolutionary War? Who knows the real reasons the south wanted to secede JUST LIKE some states wanted when they signed the constitution. We know Lee although offered to head up the north felt the loyalty to his state. That is telling as is the 10th that I recently posted with the purpose of LIMITING the feds to ONLY those rights granted in the constitution. Jefferson felt the 10th was a cornerstone to much of the constitution which is consistent with his views of the individual. I have to go...wife wanting to watch Yellowstone. Perhaps I'll add more tomorrow.
Lastly, we share an understanding that slavery was wrong and existed in the north and the south. We also share an understanding that Lincoln himself although opposed never went to war over slavery, but to try to keep the union together. He was willing to let it slowly die and prevent new owners out west. BTW, that old drunk general (Grant) that was almost dropped out of the army that Lincoln promoted "because he would fight" when McClellan would not or was never ready ended up releasing his wife's four slaves and with that Said Lee and Stonewall Jackson were supporting schooling for slaves out of their own money. There is always more in a messy war...