Robert K. Krick stated once (and I'm sorry that I can't put my mouse and click directly on his quote) that in researching over 100,000 individual Confederate soldiers, he could only identify 20-30 as being non white. But because someone reading his comment would invariably add a bunch of zeroes to the number, he would make no comment on the subject. If I can find his actual quote I will send it to you. But that is the gist of it.
Oh....here ya go. Check out "North and South" magazine. Volume 10, No. 2. I just googled it. Can't remember where I first read his comment. A man of impeccable credentials.