This may be quite a stretch but there was a soldier with the 1st Choctaw Battalion MS Cavalry by the name of James Davis. I realize this is a flip of the name of the man you are looking for but it could have been a clerical mistake somewhere along the line. A good number of the men in this unit only were recorded by one name and there was another man who was recorded only as James. Would the man you are looking for been from MS? Good luck in your search!