Lincoln never threatened to touch slavery in the states where it already existed. Lincoln was a threat to the South because he opposed the expansion of slavery into new territories, which in turn threatened any future maintenance of power in the federal government by the slaveholding interest.I think you missed the point! If the South wanted to leave the Union, and there were no slaves
I dont think the Union would have let the South leave.
The North would have invaded the south to force those states back into Union.
If you read Lincoln's plea " Come back into the union I will leave the rest open" ( in modern parlance)
Braxton Bragg
I'm not sure what the point of your statement was. If there were no slaves in the South, then why would the Southern states choose to secede?