Pure folly when one considers UK history, inherent challenges of always being United.
Ah, well now anyway we're getting to the brass tacks of sequential order of events.
The error made is in inferring that Secession is the beginning point of the U.S. Civil War...
Back up a bit. In reality, here is a simple, yet concise timeline paragraph to work from for you:
The Mexican/American War 1846-48 gave experience to the Officers of Note in the coming conflict, and gave training and relationship establishment while the Army Topographical Corps while they mapped out 5 routes of Railroad Tracks ordered by Jefferson Davis for the Technology of the 3rd Industrial Revolution, (Iron Industry) which new lands acquired in winning the War in 1848 led to heightened tensions in the 2 houses of our legislature branch, regarding adding new states free or slave; the Dred Scott Case, and the heightened aggravation of Rural vs Urban sentiments on those two events, which were exacerbated by John Brown's raid on Harpers Ferry, capture by men led by U.S. Union Army Officer Robert E. Lee. and Mr. Brown and friends subsequent execution. This led to the Highly Unusual Presidential Election of Nov. 6, 1860 which placed Lincoln of the four candidates, into office.
That was the ignition spark that started off the Civil War. It is directly a causal correlation with S. Carolina seceding in January, 6 more soon after, then four that bordered them and felt they were between a rock and a hard place, concurred; all prior to Lincoln being Sworn in,
yet all precisely because he was declared the winner of the election and they saw the writing on the wall.
https://constitutioncenter.org/blog/the-day-abraham-lincoln-was-elected-president
Apologists wish to point to Fort Sumpter as the spark, a "battle" where nobody died.
The Red Hand of Ulster opines... yet does not address Cornish, Scots, Welsh, nor Irish independence desires. If one wishes to get into that discussion, that is related, yet not only is UK history relevant in this discussion, for it is essential in the establishment of Iron industry and weapons production in their former colonies, with discovery and exploitation of vast natural resources of Iron Ore, the UK also established the institution of slavery, and then was denied any input in resolving the problem that they established 240 years prior to the US Civil War.