No x, not under reasonable circumstances. I'm sorry, but the firing on a single fort in Charleston harbor simply does not give legitimacy to the military invasion and occupation of 11 states. Lincoln used it to do so, but not in any reasonable or legitimate manner.
There is a right of rebellion and a right to self-defense, but neither justified the assault on Sumter.
Sure they did. Charleston's right of self defense was being violated and threatened by the presence of a foreign military in its harbor. That military had no other business being there than to obstruct free entrance to that harbor and had already shown that was exactly what it was there to do a day earlier by firing on a confederate ship.
imagine if county or city police had fired on the state militia
Your analogy is false. The applicable description is of a foreign nation attempting to maintain a hostile army within the borders of its neighbor, as that is precisely what happened. Lincoln could not have expected to hold his forces there and exert them against entrants to the harbor without prompting action to remove them sooner or later.
What's striking is how some people who rightly object to excessive federal power and abuses justify the same sort of conduct when states or competing nations engage in it.
It certainly is striking, and stands out in perhaps no better example than those who dismiss Lincoln's conduct on the grounds that it supposedly "saved the union"
A peaceful dissolution of the union might have been possible, but a major condition of this was that the state governments and their jumped up confederation act in a conciliatory fashion and didn't demand complete sovereignty until separation had been effected. The need to act out one's emotions or to solidify the Confederacy by, as a correspondent of Davis's said, "sprinkling it with blood" proved too strong for the rebels. The secessionist leaders behaved in a manner that would be irresponsible at any time and foolish and criminal in the heated atmosphere of the 19th century.
That's like saying the bombing of a single naval base in Hawaii did not legitimize the atomic destruction of two civilian cities. Accepting for a moment that the confederate claims of independence was valid, then the confederacy initiated hostilities at Sumter and officially declared war a few days later. The Union had war forced on them and carried it out to the end. And that included sending troops into the south.
Charleston's right of self defense was being violated and threatened by the presence of a foreign military in its harbor.
That in and of itself is no more cause for war than is the U.S. Naval base at Guantanamo Bay. Does Cuba have the right to shell it into submission and occupy it? I would say not. Charleston was in no danger. The confederacy itself was in no danger. Had Lincoln landed a few hundred more troops, or a few thousand for that matter, the threat would not have changed. But the south felt the need to begin the war then and there. They sowed the wind and reaped the whirlwind. They have nobody to blame for the suffering that happened afterwards except themselves.