What was the Civil War fought over?

Today's Advocate literally cannot say it was about slavery.

The Civil War involved a central question of civil society. Would we be a nation bound by a common commitment to constitutional order, or a country compromised by the chaos of factionalism? The conclusion of that conflict, purchased by the blood and anguish of an America divided against itself, was supposed to make us whole once more.

The Civil War happened because people weren't bi-partisan enough, apparently.  Who writes the Advocate editorials? I just think if they're gonna blame "both sides" for the Charlottesville violence then they ought to at least put their name to it. 

Update: See also Chris Lehmann on the kind of Bothsidesism in evidence at the Advocate today. 

The above-the-fray notion that “both sides do it” is a species of magical thinking perpetrated by those with a deep institutional investment in upholding status-quo power relations: network presidents, centrist pundits, the Atlantic’s editorial politburo, and moguls of various monotonous description. So by both sociopathic personal temperament and class outlook, Trump has adopted the same blame-dodging as protective coloring (as it were).