World War I has been called the «The Chemist’s War»; not only for the extend of the use of the chemical weapons in the war, but also for the complicity of the scientific and engineering efforts to create and select the most appropriate chemical agents for military use, to improve the procedures of their production, and to discover the most lethal and effective techniques for their usage and deployment in warfare. The involvement of chemical weaponry was deemed necessary at the first stages of war, given the devastating effects that the trench warfare had induced on the troops, where battles lasted months and hundreds of thousands of casualties had to be suffered for a warring side to advance merely several kilometers. While the effect that the chemical weapons had for the termination of the trench warfare is debatable, they constituted the terror of the soldiers at the trenches.
A Weapon of Mass Destruction
Chemical Weapons are not a conventional type of weapon. Alongside Nuclear Weapons and Biological Weapons, they are classified as Weapons of Mass Destruction (WMDs) due to the great difficulty of controlling their impact, the de facto impossibility of discriminating between combatants and the civilian population, and the inability of avoiding the pollution/destruction of the natural environment. But what does actually classify as a Chemical Weapon? From the hydrogen cyanide blood agent, more commonly known as Zyklon B, used for the horrendous Nazi crimes in the Holocaust and accountable for the largest death toll by chemical weaponry in history, to phosgene and chlorine gases, the differences are vast. Even tear gas, pepper spray and other less-than-lethal weapons are classified as Chemical Weapons and are universally banned in interstate armed conflicts under International Treaty Law and International Customary Law.
According to the Organization for the Prohibition of Chemical Weapons (OPCW), Chemical Weapons can be defined as: « […] any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action.»; Moreover, the definition provided by the OPCW is extended to include even: «Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled» noting that they also «are considered weapons themselves».
The Legal Framework a priori to the War
Already from the end of the 19th century, the major European powers, predicted the calamitous effects that the usage of chemical weaponry could bring upon the soldiers and civilians alike in the event of an extended European war. During the international Hague Conference in 1899, the representatives of the participating States discussed the contingency of deployment of chemical weapons in an armed conflict. The final Convention that was signed in 1899 prohibited the usage of projectiles, «the sole object of which is the diffusion of asphyxiating or deleterious gases». Several years later, the Hague Convention of 1907 reaffirmed the provisions which concerned the banning of chemical weapons and extended the prohibition to poisonous weapons as well. The Hague Conventions of 1899 and 1907 were amongst the first treaties that referred to «war crimes», and the use of chemical weapons constitute, under the scope of those treaties, a war crime too. However, the interpretation of the extant at the time International Law differed greatly between the countries (e.g. France considered the use of tear gas compatible with the legal framework); at the end of the war, all major belligerents had violated the Conventions, having used chemical weapons during the war. Signatory parties to the Conventions were all the major belligerents of the Great War, apart from the United States, Italy and Ottoman Empire.
Types of Chemical Weaponry
Tear gas consist of chemical agents which inflict damage to the mucous membranes of the respiratory system and are classified as a less-than-lethal chemical weapon. The chemical agents contained in tear gas provoke tearing and intense pain at the eyes, respiratory problems, skin irritation and occasionally temporary blindness. Tear gas was the most used chemical weapon during World War I. Despite being a less-than-lethal weapon, the chemical agents contained in the tear gas during the First World War, were more toxic that the ones currently in use from the security forces around the world, a factor which contributed to the amplified effects of the symptoms and could cause additionally bleeding from the eyes.
Since the Hague Conventions forbade specifically the «launching of projectiles containing asphyxiating or poisonous gas», it remained ambiguous whether tear gas constituted a prohibited chemical weapon. Tear gas was the first chemical weapon deployed in the war, already from August 1914 (the first month of the war). Although there is a misconception that it was Germany which used chemical weapons for the first time, it was actually France which did so, with the hurling of tear gas bombs (xylyl bromide) against the Germans.
Chlorine gas usually comprised a yellow-green cloud and was easily visible. Having been described by soldiers as having a distinctive smell of a mixture of pepper and pineapple, chlorine was a by-product of the dye industry and reacted with the water found in the mucous membranes of the lungs, creating hydrochloric acid which is destructive for the living tissues of the human organism, and potentially lethal. However, a relative high concertation ratio in the human body was required for death to occur, and gas masks were an effective deterrent against the chlorine gas. The German military high command intended for the chlorine gas to be an effective, but not a per se deadly weapon, which would force the enemy soldiers to relocate from the trenches to the ground surface so that they get attacked by conventional weapons afterwards. Also, due to the use of chlorine, the battlefield could change dramatically, with the trees’ leaves turning white and most of the flora losing its original colors. German chemist and later to be a Nobel laureate Fritz Haber, pioneered the military use of chlorine gas and its applications in the battlefield.
The narratives of the victims of chlorine gas constitute a horrific tribute to its potential devastating effects. One British soldier reflected that: «it was the most fiendish, wicked thing he has ever seen», while Sergeant Elmer W. Cotton, who served at the British Army at the time, provides a more dismal and vivid description. Taken from his diary: « [soldiers] propped up against a wall…-all gassed- their color was black, green & blue, tongue hanging out & eyes staring- one or two were dead and others beyond human aid, some were coughing up green froth from their lungs».
Phosgene gas was the next step at the deployment of chemical weaponry. It was first used by the French, following the mass deployment of chlorine gas by the Germans. The chemical agents contained in phosgene were more toxic than those contained in chlorine. Phosgene was colorless, and it had a slight odor of «moldy hay». All accounts agree that it was extremely difficult to detect. Victims affected by phosgene usually displayed symptoms 24 hours or longer after the exposure to the gas. The factor that those exposed did not succumb immediately, was considered a significant disadvantage of the weapon since soldiers initially affected, were able to fight normally, without usually knowing that they had been exposed to a highly toxic chemical agent. However, seemingly battle-ready and healthy soldiers were completely incapacitated the following day. Phosgene gas, despite not being so infamous in the public conscience, was by far the deadliest of the chemical weapons used, accounting for about 85% of the total casualties caused by chemical weapons.
Moreover, at the later stages of the war, a new technique was invented called «White Star» by the British. White Star was the acme of the chemical weapons before the initial deployment of the Mustard Gas. While Phosgene was more lethal than Chlorine, it was considerably more mass heavy, making its diffusion slower. Using the White Star technique, the combatants combined Chlorine and Phosgene Gases together, which was almost as mobile as Chlorine, but contained the high toxicity of the Phosgene Gas too.
Mustard Gas was by far the most notorious chemical weapon, having been demonized in the conscience of soldiers and public alike. It was extremely painful, and provoked huge blisters to skins, incapacitating the exposed victims’ moments after physically interacting with it. In effect, the victims were crippled almost immediately. It had a distinctive yellow-brown color and was used for the first by the Germans against British and Canadian soldiers, and later against the French army at Ypres, in 1917. Unlike the other gases which were slowly and progressively scattered by the wind, mustard gas had a relative heavy mass which made it to «settle» in ruptures of the ground, ditches, and trenches. That factor often rendered the advancement of troops difficult or impossible from the parts where the weapon had been used.
Moreover, the treatment and care of the victims was extremely difficult. Gas masks provided no use against mustard gas, while purpose-built remedies and special medical supervision were required. A fully effective treatment was nonexistent at the time, and for many who were exposed and survived, the health consequences were lifelong. As veteran Albert Marshal notes: «The gas is still with me today. It makes me itch every morning and at six every night. You can see my skin all dry. Tonight, my arm will itch from the top to the elbow. And so will the back of my neck. It feels like a needle pricking you. And that’s from seventy years ago.» Also, it is worth noting that one of victims of Mustard Gas was Adolf Hitler himself, who served as corporal in the Bavarian Army at the time and got exposed to Mustard Gas on October 1918. He got discharged and spent several months in a hospital near Berlin with acute pain in the eyes.
Case Study: Second Battle of Ypres 1915
Chlorine Gas was used at the Second Battle of Ypres for the first time by the Germans. The initial German plan included a chemical attack with only tear gas and possessed skepticism for a chlorine attack, but after consultations of the German officers with German chemist mastermind Fritz Haber it was decided to use Chlorine Gas instead. The tactical planning of the battle included the installation of more than 5.500 underground cylinders which were loaded with chlorine at liquid form. The chlorine would then be heated, and it would turn into gas, with the wind transferring it to the trenches of the Entente. German scientists had studied the winds at the area for weeks prior to the battle as to execute the plan under the best possible conditions.
When the plan was set into motion, ambush was achieved with complete strategic effectiveness. The French side, having not witnessed a chemical attack of that kind or magnitude before, were completely unprepared and suffered heavy casualties (around 6.000 dead and over 10.000 injured). The French soldiers during their effort to escape the chlorine clouds ran out of the trenches disjointedly and in chaotic retreat and suffered more casualties due to German artillery. However, surprised by the apparent success of the attack, and having no plan to send a large offensive force in after the gas, the Germans were unable to take advantage of the situation. Within days, both armies once again faced each other from the same opposing fortifications.
- Everts, Sarah, A Brief History of Chemical War (Philadelphia, PA: Science History Institute, 2015).
- Fitzgerald, Gerard J., Chemical Warfare and Medical Response During World War I, (The National Center for Biotechnology Information, US National Library of Medicine April 2008).
- Higgins Pearce, The Hague Peace Conferences And Other International Conferences Concerning The Laws And Usages Of War Texts Of Conventions With Commentaries, (London: Cambridge University Press, 1909)
- Max, Arthur, Last Post (London: Weidenfeld & Nicolson, 2005)
- Palazzo Albert, Seeking Victory on the Western Front: The British Army and Chemical Warfare in World War I (Lincoln: University of Nebraska Press, 2000).
- Organization for the Prohibition of Chemical Weapons, “Brief Description of Chemical Weapons”, Accessed on 1 January 2019.
- Taylor C. L and Taylor L. B., Chemical and Biological Warfare (New York: Franklin Watts, 1992).
 Gerard J. Fitzgerald, Chemical Warfare and Medical Response During World War I, (The National Center for Biotechnology Information, US National Library of Medicine, April 2008).
 Pearce Higgins, The Hague Peace Conferences And Other International Conferences Concerning The Laws And Usages Of War Texts Of Conventions With Commentaries, (London: The Cambridge University Press, 1909), p. 505. The full text of the Convention with commentaries can be found here: http://files.libertyfund.org/files/1053/0466_Bk.pdf Accessed on 1 January 2019.
 L. B. Taylor and C. L. Taylor, Chemical and Biological Warfare (New York: Franklin Watts, 1992).
 Albert Palazzo, Seeking Victory on the Western Front: The British Army and Chemical Warfare in World War I (Lincoln: University of Nebraska Press, 2000), p. 42.
 Arthur Max, Last Post (London: Weidenfeld & Nicolson, 2005), p. 35–36.
 Sarah Everts, A Brief History of Chemical War (Philadelphia, PA: Science History Institute, 2015).
 Fitzgerald. Chemical warfare and medical response during World War I .