If you want to understand why the South fought, let Generals Lee and Jackson explain

Clip from the movie Gods and Generals which is an incredibly accurate film. Pay close attention to why Virginia seceded, the same reason Tennessee, Arkansas, and North Carolina seceded. They no longer wished to be part of a union held together by “force of bayonet”. I use these clips because Robert Duvall and Stephen Lang were masterful as Lee and Jackson in the film

And from another clip from the film, Stonewall Jackson lays it out very clearly

Here is a piece on the character of both Lee and Jackson