Go look at a copy of the confederate constitution...better yet, let me save you the trouble:
No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed [by Congress]
The only thing the confederacy sought to escape was responsibility. They created a virtual carbon copy of the US Constitution - with one singular exception - they inserted language memorializing the perpetual ownership of other human beings. At a time when the civilized world was rejecting slavery the south sought to perpetuate and expand the activity.
As for defending itself, it should have thought of that before it initiated the hostilities.