I recently found a letter from Kirby Smith to Richard Fields agreeing to meet with him prior to Fields' trip to Richmond to address the plite of the Cherokees. The letter is dated Sept. 25, 1863 and addressed to Fields at Jefferson, Marion Co., TX. This doesn't sound like the Richard Fields who was Capt. in the 1st Regt. but no guarantee, either, that it is the Fields in the 66 photo.
BTW, there are a couple of good letters on Capt. Richard Fields in the Cher. Nation Papers.