Fire Memes for Traitor Haters

You're on the right track, but it was still all about slavery. It's just that the secessionists wanted a stronger federal enforcement of slavery, and Lincoln wasn't going to do that. The lack of enforcement, and the election of Lincoln, were the breaking points that secessionists needed to declare they no longer wished to be Americans.

It was still about slavery. The only part people get wrong was the "state's rights" horseshit. That became a conservative value during the Civil Rights era, when bigots wanted state's rights to keep discrimination as the law. At that point, bigots no longer had a majority in the federal government, and they didn't want the feds saying they had to desegregate schools and stop murdering black people.