They didn't say that secession was illegal, they said "[t]heir right to do so is now being decided by wager of battle."
Well, you've a quote here but you don't say where it came from.
That is the fly in the buttermilk on this history business. You can't just make things up, you have to build a case in the record.
And in the Prize Cases, the Court ruled that the president was authorized by the Militia Act to put down insurrrection against a state or the United States.
See how it works?
Walt
ROTFLMAO! You're killing me Walt. Do you ever read the cases YOU cite? Obviously it's from The Prize Cases, 2 Black 635, 67 US 635 (1863).