“The men of the north could not be forced against their sovereign rights to tolerate the hideous monstrosity of human slavery. You’d have to kill them first....”
You know absolutely nothing of the “men of the north” when it comes to the issue of slavery. The fact is, had the “men of the north” thought for one minute that the war was to free the slaves they never would have participated in the fight. Hell, even US Grant said that. You obviously never read any Lincoln, either, as he said he didn’t care a whit about slavery, and would leave it alone if that would keep the Union intact (which right there destroys any argument that the war was to free the slaves). Aside from a small handful of firebrand abolitionists, the north didn’t care one way or another about slavery; in fact, slavery was still legal in a few states outside the confederacy, including the Yankee state of Delaware.
Look at the census of pre war north. Plenty of slaves there.