5922992 ?Gas Alarm! Ready with respirators to repel a Hun attack under cover of the deadly cloud at Loos?, 1917 circa (b/w photo) by Unknown photographer, (20th century); National Army Museum, London; (add.info.: ?Gas Alarm! Ready with respirators to repel a Hun attack under cover of the deadly cloud at Loos?, 1917 circa. Photograph, World War One, Western Front, 1917 circa. 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?.); by National Army Museum .