Dear Art,
Thank you for the link and the info. My ggreatgrandgather was free and from his papers he said he enlisted because he thought he was going to be conscripted. I have no picture of him so I do not know his color. I do have a picture of his son ( my greatgrandfather) and know that in general he and his children were very light. I am stuck trying to understand why he was imprisoned and not set free. When the prisoners were offered freedom from Rock Island, he joined the Union and fought for them.
I am reading a book on the prison and hope to dredge up a regimental history. He was associated with the light artillery so I am assuming that he pushed the heavy guns around and assisted in handling the firing supplies.