Our nation was given birth because of slavery. Our Southern partners join the revolution because they fear Domestic insurrection.
Domestic insurrection is code for "slave revolt" which was threaten by the British leadership here in the colonies....
Read the last grievance in our Declaration of independence.....read below
He has excited domestic insurrections amongst us, and has endeavoured to bring on the inhabitants of our frontiers, the merciless Indian Savages whose known rule of warfare, is an undistinguished destruction of all ages, sexes and conditions.
If the British leadership had not threaten to use slaves if war broke out with the colonies there is a better then good chance our Southern partners in the Revolution would have stayed loyal to the British crown.
The White Southern's fear of armed slaves was so great that it forced them to join forces with their Northern neighbors in war against the British crown...
Here is a link where the Royal Governor was threatening the use of slave if war broke out....
http://www.americanrevolution.org/blk.html
I want to point out that in the states that listed their grievances for seceding form the union in every case Domestic Insurrection was listed as one of the reason for the state to secede for the union. White Southerns' truly believe that Northerns' would ferment slave revolts if Lincoln as president...
White Southern fear of Domestic Insurrection led them to revolt against the British crown and a later this fear would cause them to break away form the union.