I upvoted because it's an interesting point: but I think your definition of 'civil war' is just wrong. It's people in a single nation/people group fighting to resolve differences. Limiting it to exclude things like secession is an unnatural split that doesn't have any obvious benefits. Like, some people end up fighting because 'their' side is being attacked, they don't wish for dominance but only survival ... you'd be deciding for each individual person if it was a civil war or not.