Typical load of crap from one happy to defend traitors.
Firing on federal property and stealing federal arms and installations (Sumter was a federal installation which you must be ignorant of to say such stupid things) are sufficient causes for war.
The Secessionist fools had been urging secession for 20 years. Lincoln had very little to do with that period and was, in fact, somewhat of a moderate.
The right to independence as outlined in the Declaration of Independence, makes all real property in the areas they inhabit, theirs, not the Federal governments.
If your theory were correct, the British would still be occupying forts in America. Your theory is clearly incorrect.
And no, they weren't "traitors" as the attempt to try Jefferson Davis for treason illustrates. Chief Justice Salmon P. Chase made it clear that "secession is not rebellion".
He also told Federal prosecutors that if they put Davis on trial, they would lose everything in court they had won on the battlefield.
If they can't declare Jefferson Davis a "traitor", I don't see how they could make any lesser Confederate into one.