I suspect Wiley was so light skinned, he was able to “pass over” and serve as a White.

Note the Cansler brothers of the 59th Infantry, James, the Colonel’s Cook, and Henry, a Private. They were the sons of a White women and her Father’s slave. Another brother, Hugh, served as a Colonel’s servant in the 43rd Tennessee. Henry, was so light skinned he was able to pass as a Whitel

Note also, High yellow, occasionally simply yellow (dialect: yaller, yeller), is a term for persons classified as black who also have a high proportion of white ancestry. It is a reference to the golden yellow skin tone of some mixed-race people.