Well, the propagandists had convinced many that the Constitution didn't allow it, but it certainly is not forbidden in that document. They were convinced that the Johnny Rebs were just that "rebels", rather than citizens of soveriegn states that had decided by legitimate legislative methods to dissolve their ties with the Union. It's very telling though, that even with Lincoln assasinated by a Southerner, no Southerner was tried for treason, not even Jefferson Davis and the other political leaders. Lee went home, taking his horse Traveler with him. He became the president of Washington College (now Washington and Lee University). (Traveler outlived Lee, who died in 1870, of complications from a stroke)
They were convinced that they were rebels when they opened fire on the US flag at Fort Sumter.
It's very telling though, that even with Lincoln assasinated by a Southerner, no Southerner was tried for treason, not even Jefferson Davis and the other political leaders.
What it's telling of was the decision that it was more important to "bind up the nation's wounds" than exact vengeance. You guys are always confusing mercy with justification.
Well, in a certain sense it does. If the consitution guarantees you certain rights that not even the state is allowed to remove, then secession is in effect removing you from the protections guaranteed under the bill of rights. A state cannot vote to ignore the constitution and secession is in effect doing just that.