Deadly Smoke: The Worst Chemical Weapons Attacks of the 20th Century


Chemical warfare has long been considered as one of the worst ways to fight a war. Starting in World War I the modern age of chemical warfare was brutal, painful and unforgiving. It quickly became something that the international community saw as “crossing the line” even for counties at war. The use of chemical weapons was so terrifying to the majority of the world that in 1992 the Chemical Weapons Convention was held. It restricted the creation, stockpile and use of chemical weapons. After the Chemical Weapons Convention became active in 1997, 192 countries are bound by the rules of the convention and 93% of all declared chemical weapons in the world were destroyed.

WWI phosgene gas poster. Slate

WWI Phosgene Gas

The deadliest chemical weapon used during the first World War was Phosgene gas. It was able to improve upon all the problems with chlorine gas and create something that was far more deadly and incapacitating. Phosgene was developed by French chemists and was first used during the war in 1915.

Phosgene gas is colorless and smells like “moldy hay.” It could be used on its own but it was more effective when mixed with chlorine. The chlorine/phosgene mixture spread better when released from canisters than the dense phosgene on its own. The Allies would call the mixture “white star” due to the white marking on the canisters.

It was not long before the Germans began using the chlorine/phosgene mix with their first use against the British in December 1915. Near Ypres, Belgium, 88 tons of the mixture was released by the Germans causing 1,069 casualties and 69 deaths. It proved to the Germans how effective the new chemical weapon was when compared to just chlorine. The one caveat to the gas was that it could sometimes take up to 24 hours for the symptoms of the gas to manifest.

Phosgene gas does not have the reputation of mustard gas or other chemical compounds but it was by far the deadliest chemical weapon of World War I. 36,600 tons of phosgene gas was manufactured during the war, making it second only to chlorine in terms of the quantity manufactured during the war. Out of 100,000 deaths attributed to chemical weapons attacks during World War I, 85,000 of them are attributed to Phosgene gas.

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