No, it was Fire Eaters' "Reasons for Secession" documents which first focused on slavery to justify secession.
And protecting slavery was the reason Confederates never did (until far too late) what both George Washington and Abraham Lincoln did: enlist African-Americans as fighting soldiers in the United States army.
Why?
Because Confederates well knew that enlisting blacks meant promises of freedom after the war, promises which would negate the very reason for a Confederacy in the first place.
Republicans, by stark contrast, were the party of abolition and used whatever opportunities presented to advance that cause -- the 1862 Emancipation Proclamation, for example.
DiogenesLamp: "You want to make it about slavery, because you have no other argument to justify the Northern armies invading the South."
Rubbish, the US went to war in 1861 for the same reasons as many other wars -- because we were attacked, period.
Slavery was part of the mix from the beginning, but didn't become primary until well into the Civil War.
It's formulaic and intellect-less.
I’m a Southron.