Your posting piqued my intrest since I've never heard of Chief Johnson. After a short search I found a George W. Johnson who was Captain of Company I 1st Cherokee Mounted Volunteers listed under the National Parks Service rosters and regimental history site. While this site doesn't provide more than the raw facts of his name, company and rank; it does also provide the national archives film number for his record: Film Number M818 roll 13. Enjoy the hunt for more information.

Robert