I found a photo that says it was taken at a prison in the Philippine Islands. My ancestor's life story never mentions being captured and the group looks well dressed so I assume they were guards, not inmates. The photo doesn't say which prison or its exact location. The full names of the sergeants and corporals are listed and the names match those in the roster I gave in the previous message. Plus there are a couple of additional names. I think this proves the previous roster was indeed from the war in the Philippines.
The full names are: 1st Sgt Engelhard Endres Sgt Gottlieb D. Schlewing Cpl George A. Law Cpl Marion L. Patrick Cpl L. A. Guest (can't make out the rest of the first name) Cpl Matthew J. Day Cpl Henry Smith Cpl Ernest Norman Cpl George Murray (not sure of initial, F? or I?) Cpl Oscar M. Hubbs Cpl George B. Koehler Cpl Karl R. Seidel