The founding fathers knew that they were committing treason in the eyes of the crown, and were prepared to suffer the consequences. Southerners knew that they were committing treason to the Union, yet too many of their descendents still whine about how they were treated, which was considerably better than other folks in other domestic conflicts around the world.
" Southerners knew that they were committing treason to the Union"
Road apples. The states voted to ratify the constitution--that is, to join the US--and a number of them in ratifying specifically reserved the right to withdraw at their own discretion.
They took a vote, and it was decided to withdraw. To call that treason is...well, tyrannical.
Barf. I think my ancestors and others would totally disagree. Having half your family - men, women and children brutally slaughtered, the remainder left to starve, is not 'decent' treatment.
Additionally, treason can only apply to thoise owing allegiance and receiveing protection from a sovereign. The Confederate states seceded, renouncing the allegiance to the federal government. The union government waging war on them was not 'protection' - it was coercion - which had been explicitly rejected twice in convention.