During the Civil War ex-slave Frederick Douglass observed, "There are at the present moment, many colored men in the Confederate Army doing duty not only as cooks, servants and laborers, but as real soldiers, having muskets on their shoulders and bullets in their pockets, ready to shoot down ... and do all that soldiers may do to destroy the Federal government."
Ok, I don't doubt one bit he said it, but I would want to know how he came to have this information. I doubt he ever observed it himself since he was unlikely to be wandering around southern army camps. I'd still want to see some material that was conclusive. I am still perplexed because the Confederate government was so adamantly opposed to letting blacks, free or otherwise, wear the Confederate uniform. I don't know how they would not know this was going on.