The word terrorist wasn't used back than as far as I know but they sent their military to kill them as they would terrorist who attacked them.
You're dancing around the issue, Tony. Do you consider - based on the FBI's definition of "Terrorist" the original Colonists to be terrorists? Because either you do, and you do for the Confederacy, or you don't, and can't for the Confederacy. There's no difference, other than the "why" both armies rose up. One you like, the other you don't. Fortunately the first one won, and the second one didn't. I know I'm certainly glad it worked out that way.
But I don't consider either to be terrorist groups.