More to explore:
This photo shows a mutile man from the war. The trench war often left the face vulnerable to flying shrapnel. The photo on the right shows a piece created by sculptors to give the veterans a somewhat normal appearance again. Sculptors used plaster to cast the face and create a copper mask-like piece. The pieces were then painted to look like the veteran's face. The pieces were usually hung from the ear or from glasses.
masks for injured soldiers - Google Search
civil war wounds - Google Search
wwi tin masks - Google Search
Soldier with face mask.