It was a Revolution. George Washington and the founders of this nation didn't want to depose King George III or overthrow the British Parliament. They just said enough of British rule in America.
Washington and the rest were all in rebellion against the established government and guilty of treason under British law and if they had ever been caught, they would have hanged for treason against the Crown.
The word "Secession" that gets tossed around confuses the issue and pretends that it had some legal basis. It didn't.
The only legitimate secession from a contract is when both parties agree to it or a court of law decides that the contract is null and void. Absent that, it is a contract violation or in the case of nations, a revolution.
The Civil War was a misguided revolution for the worst of causes, and thankfully, it failed.
Unlike what the British would have done as a matter of course eighty seven years earlier to the leaders of such a revolution, none of the Confederate leaders were hanged.
In fact, from Day One, secession and Confederate government were all about overthrowing Federal Government in states where Slave-Power operated.
In the seven Deep South states (South Carolina to Texas), where nearly half of all households owned slaves, there was never much doubt about popular will regarding slavery -- though Union leaders like Lincoln did believe those states retained enough love of Union to overcome secessionist impulses.
And regardless of popularity, unilateral-secession remained unconstitutional, illegal and illegitimate in Unionist eyes.
But, in four Upper South states (Virginia to Arkansas) with only about 25% slave-holding households, the issue was much more closely decided.
All of those states had large areas of few-to-no slave-holders who first opposed secession and later supplied troops for Union forces.
Those states could well be classified as "contested", and the war there, by your definition "civil war".
Indeed, one of those "contested" states split apart, forming West Virginia, while another, Eastern Tennessee attempted the same, unsuccessfully.
And the four Border States (Delaware to Missouri) had even fewer slave-holding families, typically around 10%.
There Slave-Power's political clout was not enough to overcome love of Union, and so Confederates engaged in little more than guerrilla war.
Civil War, yes, but also a war to overthrow Federal government in those states.
Beyond civil war within southern slave-holding states, the Confederacy also invaded & waged war in northern Union states and territories, including Pennsylvania, Ohio, Indiana, Kansas, Oklahoma, New Mexico and on a smaller scale several others further removed: Arizona, Colorado, California, Vermont and (we now see) even New York.
That's why any claims that "Confederates never had any intention of overthrowing the Federal Government" are really just disingenuous.
The truth is that the Confederacy was 100% as aggressive toward the Union as it could be.
If it failed to invade a certain state -- i.e., Illinois in 1862 -- the reason was not lack of ambition or plans, but rather their physical inability, in this case resulting from Grant's victories at Forts Henry and Donaldson.
In another example, Lee's 1863 march into Pennsylvania was not originally intended to be just a quick in-and-out.
What Lee intended was to set up a permanent base of operations at the great railroad center in Harrisburg, PA.
This was to be his major bargaining chip in negotiating Union surrender.
The same rule applies to the oft-repeated claim that "slavery was dying out anyway."
Yes, but the whole point of the Confederacy was to protect and expand its "peculiar institution".
A militarily successful Confederacy would become the home-base for expansions into the Caribbean and beyond: a new world-power "Empire of slavery".
It was slavery's "last best hope on earth", and when it failed, slavery failed with it.
But had it emerged successful, the world today would be a much different place.
tanknetter: "a lot of the fighting - exceptionally bitter and viscous - took place outside the scope of control of the CSA leadership and senior generals."
Sure, but also some within their control, of which all three assaults on Chambersburg, PA, and the Lawrence (Kansas) Massacre are examples.