When we think of the horrors of large scale warfare we naturally think of WW2. But the first World War was our actual introduction to the lethality of modern war. Tanks, machine guns, and war planes all saw their origins in the Great War. That said the one weapon whose image is the most inseparable from the terrors of WW1 was the gases that were dropped on the trenches, giving us the image of soldiers marching in gas masks through a cloud of death.

Chlorine gas

Chlorine Gas ( CL2 )

Originally a noxious byproduct of their dye industry, chlorine gas first saw use by the Germans in the April of 1915. Soon both sides were using it filling the battlefields with its eerie greenish haze. Chlorine was mostly an effective form of tear gas since when it mixed with the water in tears or mucus it forms Hydro Chloric Acid causing the eyes and throat to burn. What separated this from other forms of tear gas was that in high amounts it would make the lungs fill with fluid until the victim could no longer breathe. After it saw deadly use in the battle of Ypres killing over a 1000 Russian soldiers that the iconic gas masks made their debut.

Burns from mustard gas.

Mustard Gas ( C4H8Cl2S )

After the success of chlorine a similar but even nastier gas was developed in 1917. Mustard gas as it became known because of its thick yellowish color and pungent smell quickly became infamous and remains so to this day. Like chlorine the gas would burn the lungs and throat causing affixation. Unlike chlorine though it would burn the skin causing nasty blisters. Mustard gas was also extremely hard to get rid of and could last as a residue for weeks burning anyone who touched anything covered in it. While it certainly wasn’t the most deadly of the gases soldiers coming home scared from its effects illustrated for the public how horrible the war had become.

A poster on how to recognize phosgene.

Phosgene ( COCl2.)

While mustard gas was iconic it was the ghostly threat of phosgene that by far did most of the killing. Frist used by the French in 1915, phosgene was colorless and the only sign of it was the hard to detect smell of wet hay but by then it was probably already too late. The gas worked by attacking the lungs in such a way that they could no longer absorb oxygen. The effects could take over a day to be noticed meaning that one day a trench worth of men could be fighting and the next all dead from a near invisible danger. In a devious cocktail phosgene was often mixed with chlorine since the phosgene added lethality while the chlorine helped the gases to spread.

In total an estimated 90,000 men died from gas in WW1 which pales in comparison to those who died from other causes like illness or the cold. It was however the over one million men that returned form the trenches with awful stories of the time they suffered from the gas that cemented its status as a weapon that crossed the line. In 1925 the world’s leaders gathered in Geneva to sign the Geneva protocol banning the use of lethal gas in warfare. But despite its banned status gas is still used by despots over 100 years later to today as a weapon of terror.


Chemical Warfare: Poison Gases in World War 1