"Uh, that war was comitted by the Davis government which fired upon Union forces lawfully stationed in a federal facility"
And I suppose if North Korea had a military facility in New York Harbor we shouldn't fire on them either.
As anologies go that one is pretty thin. Fort Sumter was a federal facility built with U.S. taxpayer money in the harbor of a city in the United States. It was that way before South Carolina entered into rebellion and there was no reason why the troops there should have just walked away from it. The troops there had committed no hostile acts. They did not interfere in any way with the shipping traffic in or out of the harbor. They posed no threat to the people in Charleston. Yet the confederates felt compelled to initiate hostilities then and there.