They weren't rebels. They weren't trying to take over the government, they were trying to separate from it. They also did not start the war.
It can be said that Anderson started the war in December of 1860 by forceably seizing a crucial fortress at the entrance of one of their major harbors. A fortress to which they consented with the understanding that it was being built to protect them, not oppress or subjugate them.
Any American president who didn’t simply want to let the country fall apart would have done something like that.
Analogy on a smaller scale is this. If a woman wants to leave you, you have the right to hold her by force and beat her until she consents to your unwanted control.
A union voluntarily joined should have been able to be voluntarily left. The Declaration of Independence clearly states they had that right, but power always wants to subjugate regardless of principles.
The fort was federal property and was built by the federal government. South Carolina had provided the space. I don't say the land, because I don't believe it was land at the time. If the state wanted it back they could have gone to court.
Analogy on a smaller scale is this. If a woman wants to leave you, you have the right to hold her by force and beat her until she consents to your unwanted control.
A particularly stupid analogy. Turn it around. If a man wants to run out on his family, he still has responsibilities and the matter has to be decided in the courts.
Of course some will argue that Missouri, Maryland and Kentucky were coerced to remain in the Union, so they didn't actually get to chose for themselves anyways.
And others will argue that they were being coerced to leave. Force and fraud were already involved on the secessionist side.