Chemical Warfare in the Twentieth Century

The First World War: A gas sentry ringing an alarm at Fleurbaix, 15 miles south of Ypres. Gas was first used on the Western Front by the Germans during the Second Battle of Ypres in April 1915. Chlorine was the first gas to be employed , followed by phosgene in December of that year. Various warning bells were used in the trenches, bells, rattles, empty shell cases among them. The soldier in the photograph is wearing the P helmet which was used from November 1915 until the end of 1916. The P helmet replaced the earlier and similarly shaped 'Hypo' helmet, and was impregnated with hyposulphite of soda and phenate so as to protect the wearer from both chlorine and phosgene gas. The P helmet had glass eyepieces and a mouthpiece outlet valve.