Nonsense. The South did not see the situation as a “controversy” that needed to be resolved by court. They just wanted to exercise their God-given right to self rule. And they only “wanted war” in the context of, if you do allow us our right to self-rule then, bring it on.
It wasn’t that the rebels “knew they had no case”, having a “case” wasn’t and never will be germane to having the freedom to self-rule.
Except they didn’t.
Their concept of self rule was to deny self rule to US states which did not permit slavery, to the US government which was a union of the people which preceded the US constitution, and to steal US property and imprison US citizens who did not support slavery.