The problem with this idea is that the Southrons had already threatened to leave the Union should Fremont be elected in 1856. It was the Republican Party that the Confederates could not abide. And what was it that set the Republicans part from the Whigs? I mean, the Southern Democrats never called them “black Whigs, did they?” Nope, it was the paranoia of the abolitionist movement that struck fear into the heart of Johnny Reb.
I think it was pretty well established that they weren't terribly happy about being in the Union by this point. Not only were they being taxed far in excess of everyone else, but the Government kept spending the money to prop up Northern Industries. Also they were constantly getting harangued by their "moral superiors" in the North who regarded them as "Deplorables" that were "clinging to their guns and their religion."
In other words, the same way modern Liberals from the same parts of the country treat people today.
Nope, it was the paranoia of the abolitionist movement that struck fear into the heart of Johnny Reb.
Well that's the propaganda that keeps getting repeated even though the actual facts on the ground do not support it. As I have noted numerous times, it wasn't possible to expand slavery, and it wasn't possible to eliminate it either. With both things demonstrably false, how do people keep claiming this was behind anything?
They just lie. And then they repeat the lie, over and over.