Erm... don't be to hard on "yankees". I am, myself, a "Yankee". (Iowa born and raised. I happen to live in Oklahoma; but I was born an Iowa Yankee, from a long line of German-immigrant Iowa Yankees).
The war was not "Yankees versus Rebs"; that implies a uniformity of allegiances which simply did not exist. Rather, it was a Federal Government invasion of an independent American nation. It was, as I have said, The War of Federal Aggression.
Sorry for the nit-pick... but I can't claim to be a Southron, because I ain't. By birth, breeding, and lineage, I'm a Yankee myself.
But it sure is nice down here. The winters in Iowa are practically cold enough to freeze steel.
Careful. Someone will want to jail you for being a Copperhead.
Since the U.S. and it's allies eventually invaded Japan and Germany as part of their war effort, then would you term the Second World War as The War of Allied Aggression?