Which compromise do you think could have best prevented the Civil War from occurring

The Civil War was caused because part of the US was supporting slaves, and the other half was against slaves. A compromise that let both sides be, one having slaves and the other not, would have probably prevented the Civil War from occurring, because then both sides could just be and do what they thought would be best and mind their own business, and above all, remain peaceful.

White House Chief of Staff John Kelly stirred up controversy on Monday night when, appearing on the Fox News program "The Ingraham Angle," he said "the lack of an ability to compromise led to the Civil War."

As many historians have already noted, historically speaking, it's hard to imagine what further compromise was available by the time the war broke out, other than the South deciding not to secede or attack Ft. Sumter-and accepting the eventual abolition of slavery. It's not as if Congress didn't try. Earlier decades had seen multiple compromise efforts, including most famously the Missouri Compromise of 1820.

Morally speaking, Kelly's comments could be taken to imply that the North should have compromised with the South over slavery-a repellent view that one would hope Kelly would disclaim.

Yet the controversy also raises legitimate questions relating to the Republic itself. Without a compromise over slavery, there would've been no U. S. Constitution. What were the framers thinking? And was their compromise justifiable?

Southern states would not have ratified an abolitionist Constitution. Nor did Northerners-including those who personally opposed slavery-call for national emancipation during the 1787 Philadelphia convention