The United States Supreme Court decided that the official beginning of the war began in Lincoln's office when he declared a blockade of Southern ports.
Secession occurred because of the failure of the Constitution to protect the states.
Lincoln invaded to retake Southern raw materials used in overseas trade.
Later, he and the press invoked the slavery rationalization due to the carnage problem.
Ft. Sumter was already under siege. A siege is an act of war. An attempt to resupply it, with orders to fire if interfered with is not an “invasion”. The confederates wanted a war, and they got one. You can string individual facts into a scenario where the south was an aggrieved victim, the Union was the aggressor, and slavery had nothing to do with the war, but it’s bogus.
I hereby will take my advice from my first post on the thread and save any further breath on the subject.