Nonsense. When you think about it...
Confederates claimed & invaded three Union states, Missouri, Kentucky & West Virginia, plus Union territories of Oklahoma & New Mexico/Arizona.
They also invaded Union Maryland, Pennsylvania, Ohio, Indiana, Kansas, Oklahoma & New Mexico/Arizona.
Confederate guerilla forces operated in California, Colorado & even Vermont, among others.
In the Civil War's first 12 months more battles were fought and more Confederate soldiers died in the Union than Confederacy.
That's what makes it absurd to claim the Confederacy was not an existential threat to the United States.
Correct me if I am wrong but I think you are a black person, educated and went probably to a predominantly black college? Am I right? Perhaps you were taught by professors with their own agendas? Maybe?
Jackson requested permission to invade the North before First Bull Run. He understood the necessity to demoralize them.