[dsturnbull2049]

One argument you might make is that the democracy peace theory is really just the Anglosphere. As Bismarck put it, "never underestimate the fact that Britain and America speak the same language."

You wouldn't imagine a civil war amongst a homogenous culture. I wonder if the Parliamentarians/Royalists or the Unionists/Confederates were more culturally different than the Anglosphere cultures are today.