This is not entirely fair; a considerable proportion of Union volunteers were motivated by abolitionist sentiments, although I am not aware of any detailed information on what proportion that was (other common motivations included patriotism and unemployment).

Fair enough.

We’re left at: pretty much no white people fought in the Civil War to free black people (I’m sure there were some exceptions, but the numbers are likely so small as to be insignificant).

This is not entirely fair; a considerable proportion of Union volunteers were motivated by abolitionist sentiments, although I am not aware of any detailed information on what proportion that was (other common motivations included patriotism and unemployment). That doesn’t make the meme any less stupid, though, particularly as at least some of the abolitionist volunteers were motivated less by compassion or fellow feeling than by economics; the existence of the slave states was dragging down wages everywhere (something that continues to happen on a global scale…). Also, while a fairly small proportion of the union army were conscripts, the confederate military, by contrast, was principally composed of conscripts, many of whom resented the hell out of it. They had massive, massive problems with desertion. This is something else that ‘southern heritage’ jackasses don’t like to talk about because it completely undermines their premises.