The fact remains that claims that slavey would have died out on its own are not supported by history. Regardless of the time or the means for ending slavery, in every instance it still took government to impose it. And as I asked before, how long would it have taken for the southern states to accept the federal government forcing them to free their slaves?
The trend in the South was already apparent in 1864 where the Pat Cleburne side of the military advocated freedom and a limited enfranchisement of Blacks in exchange for military service.
And Cleburne ruined any chance he ever had of promotion by supporting his plan. It was also bitterly opposed by the overwhelming majority of his contemporaries.
The South was not fighting for slavery it was fighting for its own freedom.
But defense of the institution of slavery was by far the single most important reason for beginning the rebellion in the first place.