The first four I posted were prior to the secession of the South. This is the "lead in" aspect.
Now it's your turn:
List the reasons the Union had to keep a militia in seceeded land, and for it to invade said land.
I have yet to see one.
Please post me a reason that gave just cause for the South to secede from the Union.
Don't just put up the Constitution and say there it is.