December 19, 1915 - Phosgene Gas Attack on British Positions in Ypres
Pictured - Sikh soldiers wearing gas hoods. Less than a year after its first use, poison gas had already lost much of its potential as a decisive weapon as troops were trained how to prepare for gas attacks.
General Haig received his first test as BEF commander on December 19, when the Germans unleashed a large gas attack on the Ypres salient. This time, they used phosgene gas, ten times more deadly than the chlorine gas they had used in the first major gas attack of the war in April at the Second Battle of Ypres. But unlike that attempt, in which thousands of Allied soldiers, completely taken by surprise at the noxious clouds, had been gassed or had routed, leaving massive gaps in the lines, this time the British lines held firm. Since that fateful April British soldiers, and their counterparts in other armies, had received training and equipment on how to deal with gas.
At the ringing of a bell, and the shrill alarm of “Gas! Gas!” Tommies donned gas hoods. Unlike in early 1915, when soldiers had to make do no more with urine-soaked cloths tied over their mouths, the armies on the Western Front had now developed more sophisticated methods of protection. British soldiers donned flannel hoods impregnated with phenol and mica eye-protectors. Later models had a rubber-tipped breathing tube held between the teeth. The German created a mask with a cylindrical screw-fitted filter, the model that later became standard in all armies and until the modern day.
1,000 British troops were gassed on 19 December, as well as a number of Germans on Wytshchaete Ridge, who, by misfortune of being at a curve in the trench line, were also enveloped by the gas clouds. The British did not panic, but 120 men died from the poison gas. Phosgene had more insidious effects than chlorine. Unlike chlorine, which came in easily visible yellow-green clouds, phosgene was colorless, and It had no immediate symptoms, but twenty-four hours later soldiers who had inhaled it would begin to suffer. This had drawbacks, as soldiers were not incapacitated immediately and could continue to fight. However, it caused a certain amount of terror when men who had seemed perfectly fit the day before would suddenly convulse into spasms of agony as they coughed up their lungs. Though phosgene was more potent than chlorine, the Germans took to mixing both into their gas attacks, and later their gas shells (called White Star shells), to maximize the effects.