French sentry's helmet designed to protect the face, invented by Dr. Pollack, medical officer; the Verdun Memorial, Fleury-devant-Douaumont, France. Example shown here is attached to an engineers' helmet.
<a href="//commons.wikimedia.org/wiki/User:Janmad" title="User:Janmad">Janmad</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>