Good advice for both of us, the part about not kidding ourselves. JLC didn't own any slaves at least, nor did he fight to keep them for others.
And please don't try to tell me that the war had nothing to do with slavery. It was almost all about slavery.
If the war was entirely about slavery, then why did Virginia refuse to go out until after Lincoln called for volunteers after Fort Sumter was captured? The threat to slavery hasn't changed. To credit slavery as the sole cause is to greatly simplify the matter.
As a philosophical aside, I note that in the 1930s, pertinent and respectable scholarship blamed tariff policy for the war. What was a major issue in the 30's? Smoot-Hawley, perhaps. I suggest that the "main" cause of the war reflects society's obsession at the time. Right now, in the USofA, our obsession is with race, of course.