Shelby Foote, because Ken Burns was completely taken in by his genteel southern accent and faux-erudite aphorisms, did more to obfuscate the causes of the Civil War and steer popular memory away from race and slavery than perhaps any public figure.
Nearly 180,000 Black men served in the Union Army. Another 19,000 in the Navy. Black soldiers accounted for roughly 10% of Union military deaths. A large portion of each were formerly enslaved.
I imagine they gave a damn about slavery.