In Colin Woodard's American Nations he makes two fairly bold claims. First he claims that at the very beginning of the American Civil War only the New England states were willing to use force to keep the USA together, the other eventual Union states lying between the Confederacy and New England had no desire for war and would have remained neutral making a war impossible and succession feasible. He then argues that the Confederate attack on Fort Sumter whipped these central states into patriotism and bellicosity, they rallied round the flag and the war was able to occur.
His second claim is even bolder; that the Confederate succession would have possibly led to two further successions. Firstly New York City as a sort of independent city state and secondly a Central Confederacy consisting of non-slave/non-New England states like Pennsylvania, Ohio, Indiana, etc.
It's really hard to find objective information on the American Civil War's start with so much ideology surrounding the event. Is Woodard's argument reasonable? Would Allowing Fort Sumter to stand and the Confederacy taking no aggressive actions have made war impossible and Southern succession feasible? Could it actually have ended in the break of the USA into four separate states?
Is Woodard's argument reasonable?
You could make a case for it. Woodard certainly did. I don't particularly agree with all of his points, but I don't think any of them are without merit.
Would Allowing Fort Sumter to stand and the Confederacy taking no aggressive actions have made war impossible and Southern succession feasible?
In his inaugural address, Lincoln said to the South:
In your hands, my dissatisfied fellow countrymen, and not in mine, is the momentous issue of civil war. The government will not assail you. You can have no conflict without being yourselves the aggressors. You have no oath registered in Heaven to destroy the government, while I shall have the most solemn one to "preserve, protect, and defend it."
This was actually a pretty clever bit of politics; the North wanted the maintenance of the Union but was leery of a conflict; Lincoln wanted the maintenance of the Union and pretty much needed a war to put down the rebellion, but he didn't want to be seen as the aggressor of that conflict. So what he did was to hold onto the Union-occupied army forts in secessionist territories - and refused to negotiate peace with the nascent Confederacy. To the Confederate government, the occupation of the forts by a "foreign power" was both an implicit threat and a political thorn in their side, since it suggested they weren't capable of securing their territory. Eventually, Lincoln sent out a relief mission to provision Fort Sumter - and this is what precipitated the Confederates to besiege it, and their "aggressive" act gave Lincoln the excuse he needed to call up troops to defend the Union and put down the rebellion (and that, in turn, is what polarized the Border states, et al.)
Now, the South could have let Lincoln provision the Fort - but it would have probably just been delaying the inevitable. All it would take is a single incident to serve as pretext for an armed conflict. Richard Hofstader goes into this a bit more in Abraham Lincoln And the Self-Made Myth, if you're interested.
Could it actually have ended in the break of the USA into four separate states?
This is a little harder to judge. It is true that in early 1861, New York Mayor Fernando Wood had proposed to the people of New York City that it secede as an independent city.
He then asked "why should not New York City, instead of supporting by her contributions in revenue two-thirds of the expenses of the United States, become also equally independent? As a free city, with but a nominal duty on imports, her local government could be supported without taxation upon her people...
It is equally true that there was real division in the Confederacy, and a successful rebellion might have led to further partitions - but I know Pennsylvania was pretty pro-Union, so I'm less convinced of his arguments there.