Something I wish to point out was the threat analysis which was done by the Financial Elite of the North East. In 1861, they did not know how many states would ultimately join the Confederacy, so they would have regarded the threat that Missouri, Kentucky, Maryland and Delaware joining the Confederacy as a real possibility.
In other words, they made plans in accordance with what they thought could or would likely happen, because they had no way at the time of knowing for sure what was going to happen. That it ultimately did not happen could not have been known to them at the time.
Meaning, they saw the potential economic loss of those other states joining the Confederacy and responded accordingly.
I think war was a necessary step to prevent future secessions. Once the other states saw the increased profits from free trade in an independent South, the pressure would be on to join them. Of course this leaves the North Eastern trade monopolists in a bad position.
No, you know perfectly well that Jefferson Davis started war at Fort Sumter to force reluctant Union states like Virginia and Tennessee to switch sides and join the Confederacy's war against the United States.
Of course, once war started then the Union did everything possible to prevent Border South states from joining the Confederacy.