It was not over a difference of opinions?
Or that those opinions were expressed in an election?
Much deeper issues than who was elected President. The wheels were set in motion...the only thing that was unknown was when the actual shooting war would start. Hell when Brown's Rebellion happened Lee was still a Lt. Colonel in the U.S. Army and he led a platoon of Marines to apprehend Brown and his gang.
The issue of slavery is the reason the Framers adopted the 3/5ths Compromise.
The North says it was a war about slavery and the South says it was a war about states rights. Both...to a certain extent are right.
But Lincoln's election was neither the cause nor the spark for the Civil Was as jspb insists it was.