Just curious here. For an act to be illegal it has to violate a law. Which law was violated by the Southern States' secession?
Don’t you need an Act of Congress to secede?
The Constitution. You know that Chief Justice Chase who Benson quoted? Look up what he had to say on the matter. Texas v White, 1869.
Secession is unconstitutional. There is no enacted law prohibiting, but there is little doubt that Congress could enact such a law (though why it would who knows).
There is no provision for leaving the Union. Once the states agreed to join they were stuck for better or worse.
“Just curious here. For an act to be illegal it has to violate a law. Which law was violated by the Southern States’ secession?”
Wanna know what made it illegal?
The North Won. Simple as that, really. The winner makes the rules.
However, look at history. Which part of the country now dominates national politics? In a very real way, the South lost won war, but won another. The country is more conservative, and dare I say it, more southern.