Really? Who? What nation recognized the confederacy as an independent nation and dealt with them on that basis? Nobody. Calling yourself a nation doesn't make you one. You can go around calling yourself the Grand High King of the Universe, but unless someone starts bowing and calling you 'Your Majesty" then your just another nut.
The Sovereign citizens of those seven states who formed the Confederate States of America and the Sovereign citizens of those states who later feely joined them THATS who!
Do you actually maintain that some OUTSIDE entity must recognize such an action for it to be legitimate?