W.W. Ross of Company B, 9th Texas Cavalry Regiment was captured and on prisoner list in Memphis, TN in July 1863. On August 31, 1863 he signed a Prisoners oath. I know nothing of his location after that. No pictures. I am not familar with a prisoners oath, but suspect he either joined a Union unit in the west or was freed and stayed in north for duration of war. The link below gives some history of the 9th and a book named Fighting With Ross' Texas Cavalry Brigade, the Diary of George L. Griscom, Adjutant of the 9th Texas Cavalry Regiment gives a lot more. The regiment had been fighting to the west of Vicksburg, Mississippi and morale was very low. As many as 10 men deserted and returned to Texas from Company B on Sep 1, 1863.