There were many reasons. For starters, the entire economy was based around slaves working on plantations of things like tobacco or for making gin. Without them the state would break down because they wouldn't have the free workforce that they had when they had slaves. Also, it would also help the northern states and abolitionists since there would be more non slave than slave states.
Borderline personality disorder (BPD) is a serious mental illness characterized by pervasive instability in moods, interpersonal relationships, self-image, and behavior.
The main point of the Gettysburg Address was this: Foreign Nations, stay out of our civil war! The union has turned the tide and the rebels to will be conquered and we will be one nation again soon. For the union, the civil war was not about slavery, but about making the Union whole