“Destroying the union” is double speak. If the CSA had gained independence would their not have still been a USA? Of course there would have.
They did gain independence. They had their borders, currency, military and working government. Their US house and senators had vacated the union and returned to their respective homes. The CSA main fault was firing on ft Sumter.
Well let's put it this way. Would you expect to see statues of George Washington, John Adams, or Thomas Jefferson in Westminster Abby had the colonies lost their rebellion?