Your point is not founded either in fact or law, therefore your contention about applicable law is false on its face.
And with regard to your contention that unilateral approval was “not answered before the war” is laughable. The country was governed by law, not popular approval.
And next, of course, you know that every seceded state took the issue to their people, but you would still try to misrepresent the issue.
And finally you attempt to roll out multiple red herrings about secession, war, and respect. Why bother?
Why bother indeed.
Go on believing whatever you want and being wrong.