It would certainly be hard to imagine a Civil War reenactment without both Cavaliers and Roundheads, each (or both) of whose ideologies were deeply offensive to the other at the time, and still are to many now, if they stop to think about it.

As with all matters of historical distancing, I suppose it comes down to a question of 'how soon is too soon' to categorise a particular warring faction as belonging to history, rather than still being a living, threatening entity.