In episode 3F20, "Much Apu About Nothing" of The Simpsons, a proctor is administering an American citizenship test to Apu Nahasapeemapetilon and the following exchange occurs:
All right, here's your last question. What was the cause of the Civil War?
Actually, there were numerous causes. Aside from the obvious schism between the abolitionists and the anti-abolitionists, there were economic factors, both domestic and inter--
Wait, wait... just say slavery.
Slavery it is, sir.
It has been argued that slavery was not the cause of the American Civil War and that more specifically, essential differences between the Federalists and anti-Federalists were the true cause. My question is: with the full power of hindsight at our disposal, and keeping in mind that there was clearly not one single cause, was slavery the principal cause of the American Civil War?