A Donkey and two German soldiers wearing gas masks during World War I, 1917

The Treaty of Hague, initiated by Russia in 1899 and ratified by Germany, Austria-Hungary, the United States of America, France, Great Britain, and 21 other nations, attempted to  establish  international laws on acceptable wartime practices. One specific clause in this treaty sought to limit the use of chemical weapons on the battlefield, stating: “The Contracting Powers agree to abstain from the use of projectiles the object of which is the diffusion of asphyxiating or deleterious gases.” This section of the treaty attempted to negate a humanitarian crisis which has since been one of the world’s most sensitive wartime issues.

Early in the Great War, both sides challenged the treaty using new technology. Britain first utilized tear gas, a chemical derived from bromine and delivered via a grenade canister. Both sides considered the small scale use of chemical irritants as falling well within the scope of the Hague Treaty. By 1915, the Germans began experimenting with deadlier gases. In January 1915 German forces flooded a French trench with chlorine gas, which in high concentrations is an asphyxiant. The Germans justified this tactic as following international treaty laws because they used canisters  to disperse the chemical, instead of a projectile which was directly prohibited in the wording of the Hague Treaty.

Using poison gasses on the battlefield was tricky. In the Battle of Loos, in September 1915, the British released 140 tons of chlorine, but wind swept most of the deadly cloud back towards their own line. Throughout the Great War chemist from both the Allied and Central Powers continued to explore new, more potent killing concoctions. In 1915 French chemists discovered that mixing phosgene, a more deadly chemical, with chlorine improved the lethality of gas attacks. In 1917, Germany introduced the Great War’s most well known chemical weapon: mustard gas. Mustard gas is a sulfur derived chemical compound which causes severe blistering when it comes into contact with exposed tissues. Although not as deadly as the chlorine/phosgene mix on initial contact, mustard is heavier than air so it settles low to the ground and remains active in the environment for weeks to months. The Great War saw the first large scale use of chemical agents on the battlefield, but precautionary measures, such as gas masks, limited their lethal potential. Over the course of the war, there were approximately 1.2 million casualties caused by chemical agents, but only roughly 90,000 were fatal.

By Micheal Williams

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 Further Reading/Sources:

Jones, Simon. World War I Gas Warfare: Tactics and Equipment. Oxford: U.K., Osprey Publishing, 2007

Richter, Donald. Chemical Soldiers: British Gas Warfare in World War I. Lawrence: Kansas, University Press of Kansas, 1992

Tucker, Jonathan. War of Nerves: Chemical Warfare from World War I to Al-Qaeda. New York: New York, Knopf Doubleday Publishing Group, 2007

Faith, Thomas. Behind the Gas Mask: The U.S. Chemical Warfare Service in War and Peace. Champion: Illinois, University of Illinois Press. 2014