'Through gas and smoke, our troops advance to the final assault of Passchendaele Ridge', 1917

Photograph, World War One, Western Front (1914-1918), 1917.

The Germans first used gas against the French during the capture of Neuve Chapelle in October 1914 when they fired shells containing a chemical irritant that caused violent fits of sneezing. In March 1915 they used a form of tear gas against the French at Nieuport, and the following month chlorine gas against the Canadians at Ypres. These early experiments were but a small taste of things to come and as the war progressed all sides developed ever more lethal gases including phosgene and mustard gas.

From a collection of 101 stereoscopic photographs entitled 'The Great War'.