Nope... the war of northern aggression is quite accurate. the majority of the northern citizens (and the supreme court for that matter) saw the succession of the southern states as just. since member states of a republic have the right to leave if they decide it is in their best interest to leave... Because the moment you are not able to leave peacefully through succession... You cease being a republic and become an empire.
I'm from North Carolina. The last state to join the confederate states.. succession was something us North Carolinians did NOT favor, right up until Linclon ordered the North Carolina Militia to raise three regiments and ordered them to deploy into South Carolina to 'put down the rebellion'... In fact Zebulon Vance, our US Senator at the time was travelling through the state holding rally's to support remaining in the Union, right up until he got the telegram ordering the militia to mobilize and go into SC. At the same rally, he went from saying that NC will stay in the Union no matter what... To saying, it's time to succeed and here is why.
The states had the right to succeed, and this is why NONE of the leaders of the CSA had been tried for treason. Especially when it would have gone to the Supreme Court who would have classifed the 'Civil War' as a war of aggression against a seperate sovereign state and that the Union would have had to withdraw and pay repreations to the south thanks to Sherman's March through the south....
Besides a Republic only exists when the union that creates it is voluntary, and when that union becomes something that can be enforced, it becomes an Empire. That was one of the under current stories in Star Wars if you look hard enough.
