On the afternoon of 22 April 1915 the French Army in Ypres watched as an unusual cloud moved towards them. The cloud was chlorine gas, the latest weapon of the German Army. Its appearance heralded the start of a new horror for soldiers on the Western Front.
Chlorine and the deadlier, colourless phosgene gas introduced in late 1915 worked by irritating the lungs and caused asphyxiation in high doses. Phosgene was responsible for a large proportion of gas-related fatalities during the war. Mustard gas was introduced in 1917. As well as irritating the lungs, it was absorbed into the skin, causing terrible blisters and temporary blindness.
The introduction of gas initiated developments to combat its effectiveness. Gas alarms were built to warn men of approaching gas, and fans were issued to help sweep the gases out of the trenches. Within a month of the first gas attack, British soldiers were being issued with protection. The Black Veil Respirator was a pad of cotton waste, coated in sodium hyposulphate, sodium carbonate and glycerine, which was wrapped around the soldier’s mouth. This was later superseded by the P and PH hoods, which covered the whole head with gas resistant material.
In 1916, the British Army introduced the small box respirator. Consisting of a rubberised fabric mask connected to a canister by a rubber hose, it filtered the air using charcoal and other substances. Small box respirators were carried by British and Dominion soldiers in a canvas haversack, which was worn on the chest when at the front lines.