Belgian machinegunners with very early gas masks during World War I.
Photographer unknown; book more than 70 years old.
From: The Great War: The Standard History of the All Europe Conflict (volume four) edited by H. W. Wilson and J. A. Hammerton (Amalgamated Press, London 1915), as found on: www.firstworldwar.com.<a rel="nofollow" class="external autonumber" href="http://www.firstworldwar.com/photos/graphics/gw_belggasprot_01.jpg">[1]</a> Original text on web site is copyrighted, original photo is from a book more than 70 years old.