British soldiers advancing under cover of gas and smoke, France, World War I, 1916. Artist: Realistic Travels Publishers [Getty Images]

British soldiers advancing under cover of gas and smoke, France, World War I, 1916. A break in the German lines is made through to Serre and Thiepval during the Battle of the Somme. Photo from a captured prisoner. Stereoscopic card detail. (Photo by The Print Collector/Print Collector/Getty Images)

Hulton Archive Print Collector