Ken Martin,
The following "Thomas Miller" is not from the 1st Chickasaw Infantry, but may be of interest.
One "Thomas Miller" is in the 1863 cumulative listing of Stand Watie’s Cherokee regiment on vIIpA-347 of my book.
Stand Watie’s
Regiment 2 Company C
Miller, Andrew
Miller, George
Miller, John
Miller, Thomas
Patti, prochette@Juno.com