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Charging through a toxic cloud, masked German soldiers stage a gas attack on British lines in Flanders. (AKG-Images)

Why chemical weapons are taboo.

THE 22ND OF APRIL 1915 along the Ypres Salient in France was a warm, sunny day. In late afternoon a cool breeze began blowing from the northeast to­ward the Allied lines. The Great War had been raging for eight months and was becoming a stalemate. At 5 p.m. the German army, seeking a decisive breakthrough, opened 6,000 gas cylinders, releasing 168 metric tons of liquid chlorine that would kill almost 5,000 Allied soldiers, wound another 10,000, and open a huge hole in the western front. Guarding this part of the salient stood French reservists and Algerian soldiers. These troops, new to the trenches, mounted the fire steps and prepared to repel a German assault. Instead they saw a giant cloud of greenish-yellow gas coming toward them; their eyes began to burn, throats tickled, and mouths filled with a pungent, metallic taste. Once the mist enveloped the lines, soldiers collapsed in agony clutching their throats as the chlorine stripped the lining of their bronchial tubes and caused blindness, coughing, violent nausea, headaches, and chest pains. Some men buried their faces in the earth, attempting to alleviate their pain, while others abandoned their trenches and ran, not realizing the harder they exerted themselves the more gas they sucked in. Many coughed so violently that their lungs ruptured. The inflammation from the chlorine produced a yellowish fluid that blocked windpipes, caused frothing at the mouth, and even filled lungs—men essentially drowned on dry land. A British soldier wrote in his diary of an encounter with a fleeing Algerian gas victim: “One man came running through our lines. An officer of ours held him up with a leveled revolver, ‘What’s the matter, you bloody lot of cowards?’ says he. The Zouave was frothing at the mouth, his eyes started from their sockets, and he fell writhing at the officer’s feet.”

Chemical warfare had begun.


THE HISTORY OF WARFARE IS REPLETE with examples of weaponry that, when first introduced to the battlefield, drew visceral reactions from combatants and civilians alike. Even in the modern era, the initial use of aircraft and submarines as offensive weapons of war caused some to call for outright banishment of these new and terrifying machines. As dreadful as these new armaments appeared, to many they were an inevitable manifestation of the industrial age. Aircraft and submarines quickly gained legitimacy on both the battlefield and home front, becoming lawful weapons of war.

The introduction of mass-produced chemical weapons to the battlefields of the First World War, however, incited an impassioned international debate over the legitimate use of poison gas. The debate was actually not new; it had been ongoing since the latter half of the 19th century. But, confronted with the immediate, undeniably horrific results of chemical warfare on the western front, abstract philosophical discussion quickly became public, clamorous opposition. For the next 20 years, the use of chemical weapons galvanized public and international opinion in the United States and Europe, as many pushed for regulation and outright bans, while others advocated for continued development and use of poison gas.

Slowly, with great resistance from military and government leadership, and even from some veterans of the Great War, an international consensus emerged repudiating poison gas as a legitimate weapon of warfare. Certainly, the First World War witnessed novel and more varied ways to maim and kill with more powerful and accurate artillery, strategic bombing of cities, the use of barbed wire on the front, and submarine attacks on civilian shipping, among other murderous methods. Poison gas, however, remained a special category of weaponry, widely regarded as so abhorrent that the international community outlawed its use in warfare.

Chemical or poisoned weapons are not a recent phenomenon. They have a long tradition in both Western and Eastern warfare, albeit on a far smaller scale than in the First World War. Almost 2,000 years ago Persian invaders introduced poisonous smoke into a tunnel beneath the Roman city of Dura-Europos in modern-day Syria killing at least 20 Roman soldiers. Roman armies poisoned the wells of besieged cities, the Byzantines used “Greek fire,” Greek armies used smoking chicken feathers, and the ancient Chinese used limestone powder as a riot-controlling tear gas, to name just a few. Other than a 1675 Franco-German treaty banning poisoned bullets in battle, however, international diplomacy did not attempt to regulate the production and use of chemical weapons until the last half of the 19th century. Three conferences held between 1874 and 1907 attempted to outlaw the use of chemical or poisoned weapons in warfare. The 1874 Brussels International Declaration forbade “employment of poison or poisoned weapons,” while the 1899 and 1907 First and Second International Peace Conferences in The Hague prohibited the “use of projectiles, the only object of which is the diffusion of asphyxiating or deleterious gases.” Despite the international community’s best efforts, these agreements obviously had little effect on the use of chemical weapons during the First World War.

Battles on the western front first brought the realities of chemical warfare not only to combatants but also to the general public. Industrialized production of poison gas coupled with its surprisingly effective initial use created new tactical options for commanders, the likes of which had never before been possible on such a massive scale. The initial German military deployment of liquid chlorine near the town of Ypres, Belgium, in 1915 was so effective that it opened a four-mile-wide hole in the Allied line in just 36 hours, following months of stalemated trench warfare. While it was the German high command that introduced deadly gas to the battlefield, the Allies would soon respond in kind. According to some estimates, by the end of the war, one-third of all artillery munitions contained gas.

Immediately following the war, pressure began to build to outlaw the use of chemical weapons. The people of Europe and the United States were exhausted by the mass slaughter and industrialized violence of trench warfare. News stories, graphic images, and returning veterans—many of them visibly wounded—all reminded civilians of the high price of war. Especially gruesome were those who suffered from chemical weapons’ effects, such as severe vomiting and tissue damage that included extreme burning, swelling, blistering, and discharge from the mucous membranes. The political and public fight over the legitimacy of the use of poison gas on the battlefield kept such horrifying and shocking images before the public eye.

Sides were drawn. Proponents of chemical warfare, including United States Army Chemical Warfare Service leadership and many in the civilian chemical industry, launched a full-scale public relations campaign with a constant barrage of speeches, articles, and lobbying designed to convince the American public and government officials that a ban on chemical weapons would be detrimental to national security. Chemical warfare advocates argued for continued production and use of poison gas, contending that it served as a deterrent to other nations, and was a legitimate “force multiplier.” Poison gas, they argued, was unfairly maligned for its novelty in combat, much like many other weapons when first introduced to the battlefield.

Arguing for the abolition or international regulation of chemical weapons, anti-gas activists tended to focus on the horrifying possibilities of chemical warfare in the future. The arguments that galvanized public opinion, were that poison gas was an uncontrollable, indiscriminate weapon threatening soldier and civilian alike; that poison gas was an “unclean” weapon causing torturous wounds and slow death; and that the continued development of chemical weapons could one day produce an agent capable of destroying entire cities and possibly nations. Some military leaders, such as General
P. R. C. Groves, the Royal Air Force director of air operations during the First World War, and Brigadier General Billy Mitchell, commander of all American air combat units during that war, further alarmed the public by linking the use of aircraft as a delivery system for poison gas, which could make it possible to target cities far away from the battlefield.

The debate between these two groups in the United States and western Europe created the foundation for today’s nigh universal condemnation of chemical warfare. Both sides were responsible for driving the international community to declare poison gas illegitimate. Proponents, with their vociferous lobbying for chemical warfare created a heightened fear of chemical weapons and generated pressure to regulate the use of gas in warfare. Sensationalizing the threat of chemical weapons in order to justify their usefulness paradoxically reinforced the frightening prospect of poison gas attacks. Chemical warfare opponents reacted in kind, lobbying governments and producing articles and speeches stressing the indiscriminate nature of gas, its resulting appalling wounds and death, and the mass civilian casualties it could inflict even off the battlefield.

Eventually these arguments sufficiently alarmed the public and convinced political leaders that chemical weapons were too horrific even for warfare. General John Pershing, the veteran commander in chief of the American Expeditionary Forces, stated in 1922 that “chemical warfare should be abolished among nations, as abhorrent to civilization.” A fragile international consensus to regulate gas warfare finally emerged with the signing of the 1925 Geneva Protocol prohibiting the “use in war of asphyxiating, poisonous or other gases.” Although it would take another 50 years to ratify in the U.S. Senate, the codification of chemical weapons as a category of unacceptable armament, condemned by the international community, was established seven years after its final use during the Great War.


THE USE OF POISON GAS, HOWEVER, did not end in 1918 or in 1925. While never again used on the massive scale seen during the First World War, fascist Italy used mustard gas during its 1935–1936 invasion of Ethiopia, and the Imperial Japanese Army employed chemical weapons in Manchuria starting in 1937. Iraq used chemical weapons against the Iranian military in the 1980–1988 Iran-Iraq war and gassed the Iraqi Kurdish village of Halabja, killing from 3,000 to 5,000 civilians. In 1995 Aum Shinrikyo, a Japanese apocalyptic cult, used sarin gas on the Tokyo subway, killing 13 and injuring over 5,000. Most recently, the Syrian army allegedly used chemical weapons on its own civilians during the recent Syrian civil war, killing 1,429, including 426 children.

The sporadic use of poison gas since 1918 has only solidified the special category in which chemical weapons are placed. The fact that fascist dictators, ultra-imperialists, and fanatical tyrants and terrorists have been the few to openly use chemical weapons since the signing of the 1925 Geneva Protocol reinforces the status of poison gas as an illegitimate weapon of repressive regimes. More significantly, its use on civilian populations, whether in Iraq, Tokyo, or Syria, further bolsters international condemnation of chemical weapons. Television coverage showing the gruesome effects of poison gas, particularly on women and children, and the corresponding impression that the suffering of victims is a form of torture, strengthens moral revulsion, and echoes General Pershing’s claim that chemical warfare “demoralizes the better instincts of humanity.”

A product of the First World War, the perception of chemical weapons as illegitimate weapons of war remains strong today. The antipathy toward chemical warfare hardened between the world wars, and its more recent and brazen use has reinforced this taboo.


Christopher A. Warren is a historian with the Air Force History and Museums Program in Washington, D.C. An attorney and former FBI special agent, he is writing a history of the Air National Guard.


This article originally appeared in the Winter 2014 issue (Vol. 26, No. 2) of MHQ—The Quarterly Journal of Military History with the headline: An International Red Line

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