South fired on the North; Fort Sumter.
You left out the Warship flotilla the Union had sent to Charleston, in violation of the armistice, the arrival of which provoked Beauregard into firing on the fort. (Literally. He says so in his communications.) When faced with the prospect of being attacked by both the guns of the fort, and the flotilla of warships 10 miles off of Charleston, he made the militarily prudent decision to take out one enemy force before the second one could bring it's weapons to bear.
Most people didn't even know Lincoln had sent those warships. (With several hundred armed soldiers aboard.) It gets left out of the story because it doesn't support the narrative.
Most people also don't know that Major Anderson (Commander of Ft. Sumter) was not ordered to go to Ft. Sumter. He was stationed at Fort Moultrie, which he abandoned, after spiking and burning the cannons. This came as surprise to the locals, because they had been led to believe that the Fort would be given over to them peaceably. The burning of the cannons by Major Anderson was regarded by the locals as the first belligerent act of the war.
Major Anderson decided to seize Ft. Sumter. The Fortress had never had a garrison, and Major Anderson's force was the very first time it was ever occupied, and he occupied it without authorization or orders to do so.
Suddenly the people of Charleston had Union Troops in a fortress that had never been occupied, and they were already aware of at least one Union Newspaper urging that the guns of Ft. Sumter be turned on Charleston to stop them from trading with Europe.
It would worry me too if Troops suddenly showed up there. I would be alarmed.
A lot of stuff gets papered over when people talk about what happened.