Huh?
Like Osama bin Laden gave the US an eviction notice? Like Arafat gives the Israelis an eviction notice?
So if, say, the Idaho Militia decided to secede from the Union, we'd just let them? You're living in a dream world.
Just letting the Confederates leave the Union was never an option. No way. There was only room for one United States, not two, and most especially not another one that was willing to attack us with force and arms.