What he said. Secession is not necessarily the same thing as Treason. The South believed they had a right to secede, and viewed the North as aggressive invaders.
The argument can be made that both sides were far too eager to march into war rather than resolving the matter diplomatically.
Aggressive invaders?
Who fired the first shots on Fort Sumter?????????
That war had been brewing for fifty years.
And so did much of New England prior to the Civil War. They threatened to walk away from the Union at least twice.
The argument can be made that both sides were far too eager to march into war rather than resolving the matter diplomatically.
Exactly. The issue of secession itself is far more complicated than many think. The Founders did not oppose secession per se, though they DID think it a bad idea unless there had been a "long train of abuses", to borrow the terminology of the DoI. Madison, for instance, believed States had the right to secede, but that the act of doing so constituted a "revolution" - by which he meant the very technical and specific act of changing the political structure. Hence, secession is a revolution, but it is highly doubtful that the Founders would have viewed it as "treason" in the sense that many posters on FR use the term when discussing this issue.
The Founders, across the spectrum, held to a medial position on State's rights. They did not view the States as being absolutely sovereign entities as they had come near to being under the Articles. Nor did they view them as mere provinces, as they have increasingly became in post-1865 America. They intended, with the Constitution, a true Federal system, whereby external powers and those which factored across State boundaries were divided to the Federal government, while internal powers (the majority of issues) would be reserved to the States, and to the people, who are viewed as acting THROUGH their States (this is, for instance, why the Senators were originally intended to be appointed by State legislatures, not direct election of the populace).
Instead, the States were to be largely self-governing on their internal matters, and per the idea that the Constitutional system was acceded TO by States, they retained, per the 10th amendment, the unenumerated right to secede FROM this same union - though this act, because it changes the political system, would be considered revolutionary. In short, secession went right along with the classically liberal notion of self-determination - if a political body did not wish to be associated with a larger body, union, federation, etc., then it had the right to withdraw and form its own body, or associate with another. This is how they justified the Revolution against Britain, and (technically) it applies equally to the South's situation in 1860-1. The Founders, at the same time, felt that this right was a "last resort", it was only to be used if there was a grave and terrible harm being done to those who would then be wishing to secede.
Most people between the Founders' generation and the generation which fought the Civil War understood this. The only credible opposition came from the "National Greatness" types like Andrew Jackson, Henry Clay, and Joseph Story. But, for every Joe Story arguing that secession was not provided for, there was a Bill Rawle arguing that it was. The issue was determined (though not SETTLED) by the bogus Texas v. White SCOTUS case in 1869 in which a national greatness SCOTUS operating under the auspices of the Radical Republicans ruled that secession was unconstitutional. It's not, of course, but such were the times in 1869 that a decision like that could be rammed through with ease.
For the record, I am a Midwesterner, so I don't really have a dog in the Yankee-Southron fight. My main interest is in freedom TODAY, which includes the right for political self-determination. I would say that States TODAY still have the right to secede. I would also say that the South was technically right in asserting its right to secede in 1860-1. This is tempered, however, by the fact that I do not think the South had a "long train of abuses" to necessarily justify its secession, and I certainly don't think that slavery was a reasonable justification for it at all (though I also know that slavery wasn't the ONLY reason for secession).