Yes, they most certainly did. No one argues that fact. But we support America because we agree with the principals they asserted in the Declaration. The confederate states believed in people as chattel, as did other states, but the south went to war over it. Flying the flag is supporting those principals, just like the American flag supports our Principals. That doesn't mean our actions as a country are always right, but we work to correct them. Taking down the flag that was put up at the State House in South Carolina to opposed Brown v Board of Ed., is a step in trying to correct the action. No one says YOU can't fly any flag you want. The State of South Carolina . . . well that is another matter altogether.
It was a ridiculous question to ask, no doubt. But some of you need to actually understand that the South did not commit treason.
Each of the 13 original colonies were sovereign entities, still are.
The constitution was nothing more than a contract they signed forming a union to benefit all of them. And in that contract it was specifically worded that if the contract was broken that they could leave the union.
The south followed the contract as slavery no matter how awful we think it is today was legal at the time.
When the north broke the contract over and over South Carolina actually wrote an article for secession in 1852, you should read it, it's rather enlightening.
The north broke the agreement, the south got fed up with it and seceded. Actually 4 of the states didn't secede until am army was formed to march on the south for doing something the original colonies agreed to, seceding.
Kentucky didn't secede because they didn't feel it was about abolishing slavery. As it would've and did take an ammendment to do it, and there wasn't the required vote to pass it.
So yes the original colonies did commit treason, because they had no legal right to leave the British empire. The South had every right to secede as it was part of the deal, if the deal was broken, being the constitution.