If I have the right man, the United States Army Military History Institute, Carlisle Barracks, has a number of photos and one enlisted man's letter.

George Martin

William Ray; Enlisted as a Captain, "G" Co. MO 5th Cavalry USA

USAMHI
RefBranch

5th Missouri Cavalry Regiment

Our Photo Archive includes images of individuals of this unit.

The following pertinent personal papers are in the Institute's Manuscript Archive:

Holsbauer, G. - CWMiscColl-PensionFiles (Enlisted man's letter, Apr 21, 1862)