Suppose we take as given (which I do not) that secession was legal.
It's basically the core point of my position regarding the whole matter that secession was legal. While I'm glad you're willing to - even hypothetically - entertain the notion that this is indeed the case, I remain curious as to why you won't
actually accept it.
The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
I mean, that was - and remains - the law of the land. If the Constitution doesn't delegate it to the federal government or prohibit it to the states, it remains within the scope of the states' sovereign authority (and if a state doesn't legislate on the matter, then it's for every person to decide what's right). This is the principle of subsidiarity, clear and simple. A more clear-cut case of it has rarely existed. As I always charge anyone who claims secession wasn't (or isn't) legal under the Constitution: please, do point out exactly where it delegates the power to regulate that matter to the Federal government. Spoiler: it doesn't.
That was not what the North was unwilling to accept. Consider the multitude of proposals floating around for a "Central Confederacy" of states from New York to Arkansas and everything in between (and other proposals for an independent NYC), among other things. Things were very peaceable during the first months of 1861.
What the North was unwilling to accept was secession by the sword, at Fort Sumter. As secession had never happened in the US before, and the Constitution / DoI had no explicit provision for how to handle secession, then even assuming it was potentially legal, there was no set mechanism for how to do it. In particular, there was no provision for how to handle Federal property and locations within the seceding State. As such, the North could (and did) hold the position that the fort and its supplies was Federal property, and did not secede with the rest of South Carolina (as indeed with Fort Pickens at Florida). Given that South Carolina and the nascent CSA disputed this view, they could have negotiated for its turn-over. Many views in the North, in Lincoln's cabinet, and from General-in-Chief Winfield Scott, believed that ultimately the fort would and arguably should be given to South Carolina.
You ignore a few facts here. For instance, the fact that the Federal garrisson was actually on the mainland. In the dead of night, that garrisson secretly fled to the unfinished insular fort Sumter-- and not before having sabotaged the equipment on the mainland. That's not exactly setting the stage for polite negotiations, is it? No. What it
was, however, was a direct violation of (the still quite valid and operative) instructions of the demissionary but still-in-office president Buchanan. Now, we can say Buchanan was a bag of dicks, but ignoring binding instructions to
not act provocatively or change the status quo in any way by doing literally the opposite of that... well, that's not exactly solid behaviour.
At that point, we get to this:
Here Lincoln was very canny, and sent a supply ship to the fort with food, but not with arms or reinforcements. As food was the bare necessity for the fort's inhabitants (defenders) to live, this action would preserve the status quo while allowing for diplomatic talks to go forward. It could not be reasonably considered an aggressive action. And ironically it would prove futile, because Robert Anderson judged that he would run out of food and have to surrender before the ship could arrive. But all of this was not good enough for the CSA.
Even then, they could have chosen to send a ship to intercept the Union supply ship. It would give warning to turn back and not deliver the supplies, and threaten to open fire on the supply ship only if the supply ship did not turn back. Given the warning, even this may have been defensible as a non-provocative action.
Instead, we got the bombardment of Fort Sumter.
That was what the North could not accept.
It was very canny of Lincoln,
indeed. Worked out for him, too. Of course, the status quo - as I pointed out - had already been upset by those very men in fort Sumter.
While the South Carolinians would certainly have done well to act far more cautiously, the idea that they had no right to demand the surrender of a military force in their sovereign territory is rather strange. It must hinge on the (incorrect) assumption that the secession was illegal and therefore void. But that's a false premise. South Carolina had chosen to become a sovereign country-- and was therefore under no obligation to tolerate foreign military forces within its borders. Certainly, it was obligated to guarantee them safe passage to the border
if they surrendered. But by occupying fort Sumter in the dead of night, against presidential orders, those Union forces had already proven to be hostile. They'd had months to vacate the fort. They should have done so. Afterwards, had the separation between North and South proven irreparable, the CSA should have coughed up adequate monetary compensation for all Federal property (namely, forts and other such installations) of which it had inevitably assumed control by seceding.
Had the CSA refused to grant such compensation,
that would have been grounds for war. (War against a foreign country, mind you.) But to say that a sovereign state expelling armed squatters from within its borders is somehow a crime? No. It's not. The USA was at fault for not recognising the secession and for not withdrawing its forces. The simple fact that the USA refused to even recognise that the secession was legal
in principle was fundamentally a problem. You write that the Federal position was that the fort did not secede along with SC. The truth is that the Federal position was that the secession was null and void. It was never "we will allow secession if we work out the proper details first". It was always "this is an illegal uprising, and we'd rather come to a peaceful resolution, but if not, we'll preserve the Union by force if we have to".
The sequence of negotiations should have been:
1. The USA recognises the CSA, because no matter the details, secession itself is legal.
2. The CSA and the USA exchange ambassadors, so they can actually
start negotiating.
3. The USA attempts to convince the CSA to re-join the Union. If successful, end of negotiations: the CSA re-joins the Union after a brief stint as a sovereign country. If
unsuccessful, we go to 4.
4. The USA demands that the CSA offers compensation for Federal property in the South.
5. The CSA agrees to further negotiations on proper handling of such affairs, provided the USA first evacuates all its forces from CSA territory forthwith (which is not an unreasonably demand).
6. These further negotiations actually commence (and probably drag on for ages).
The
actual sequence of negotiations was:
1. The USA refuses to recognise the CSA and also dismisses all resolutions that do not somehow end in the return of the South into the Union.
2. Unless both sides find it within themselves to find a compromise that retro-actively undoes the secession (Corwin, Crittenden, an ATL alternative), there is no space for further negotiations, because the USA has ruled those out by refusing to recognise the secession. So: end of negotiations.
War.
The claim that the USA would
totally not have waged war if the CSA had just refrained from firing on fort Sumter is, by the way, a joke. It's akin to claiming that the secession of the CSA was really about tarriffs, rather than slavery. Smoke-screen justifications for the real motives. The CSA wanted to preserve slavery, and all else was window-dressing. And the USA wanted to bring the CSA back into the Union no matter what. In the words of Abraham Lincoln himself:
I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored; the nearer the Union will be "the Union as it was." If there be those who would not save the Union, unless they could at the same time save slavery, I do not agree with them. If there be those who would not save the Union unless they could at the same time destroy slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union. I shall do less whenever I shall believe what I am doing hurts the cause, and I shall do more whenever I shall believe doing more will help the cause.
By which I certainly do not mean to imply that Lincoln was secretly a racist, as some revisionists use this quote to "denmonstrate". He ends this same letter by expressing his personal hatred of slavery-- but he makes it very clear that he'll set that aside for the sake of his paramount goal: to restore the Union. To undo the secession. As much as the war was about the preservation of slavery for the South, for the North it was about unmaking the secession. The claim that it was all an exercise to avenge fort Sumter is laughable. Lincoln was indeed canny! He
wanted the South to attack fort Sumter. He wanted an excuse. And he'd have found one, no matter what.
So let's not pretend that if the South hadn't fired on fort Sumter and had in fact behaved politely on all fronts, the North would suddenly have decided to let the South go in peace. That would
never have happened. The South wanted independence from the North, the North didn't want to grant it. Now, as to the outcome: I'm rather fne with it, except that it has created the unfortunate misconception that secession
itself is a bad thing. The fact that the CSA got crushed? As they say: "Awwww, it
couldn't have happened to nicer people."
But there is also such a thing as historical truth. The fact that they set up their own country just to safeguard their ability to own other people is clear enough when it comes to identifying the bastards. Adding false charges ("Secession was illegal! The North would
totally have let them go if it hadn't been for fort Sumter!") just tarnishes the truth. If we have to turn our conceptions of history into cartoon-like portrayals where the bad guys are cardboard villains who are wrong about
everything, then we do ourselves a disservice. In real life, even the morally wrong side can be right about certain things. And the good side can do bad things for a good reason. Hell, they can even do bad things that then produce a good outcome! (Say, an illegal war of reconquest setting the stage for the abolition of slavery...?)