Charles of Austria with the Turks, c. 1916.
That is Charles of the House of Habsburg, either as heir to the throne or already emperor, meeting with Turkish dignitaries. There is an Austrian dragoon in his helmet with his back to the camera, and a various Austrian generals. The guards are Turkish in colorful uniforms that I am unable to identify. The officers of the guard seem to have white uniforms while the enlisted men have dark coats. The only insignia I can make out is on the collar of one of the guard officers—a star and crescent.
Page by Mark Conrad, 2012.