Show me your sources. I'm not dismissing your claims out of hand, it's just that Walter E Williams articles--I found several--on this are based on such slender, suspect evidence and are published in suspect places, not in peer reviewed history journals. One of them was in the journal of the John Birch Society(!).

Frederick Douglass would have had ample reason to make fallacious claims about black Confederates: his thinking--I've read a lot by and about him--was that combat service by African American troops in the Union Army would substantiate black folks' claims to full citizenship. 

So he may have been lying simply to make Lincoln think that there was a need for the Union to mobilize black troops. Same about the newspaper article (singular) saying two companies of black Confederates marched through Augusta; in war the first casualty is truth, as someone said.

No real historian would make such an outlandish claim based on such problematic evidence. And none has.