That speech includes the following:
"Those (meaning Thomas Jefferson's) ideas, however, were fundamentally wrong. They rested upon the assumption of the equality of races. This was an error. ... Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner–stone rests, upon the great truth that the negro is not equal to the white man; that slavery — subordination to the superior race — is his natural and normal condition."
So if that was the true reason for the War Between the States, as you say - I'm very glad that the North won.