I'd say that a further case can be made that the Revolutionary War was the first civil war over race and slavery. Dunmore's proclamation resulted in at least 100,000 slaves joining the British cause.

Colonials for the most part were split evenly between the tory and rebel cause. But when Dunmore issued his proclamation, public opinion took a hard turn against the Brits. Landowners and mercantilists were aghast.