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Chemical Weapons Use Doctrine in the 20th Century

Abstract: On April 22, 1915, a new chapter in warfare began. The first systematic mass use of chemical weapons offered new and hitherto unimaginable possibilities in planning and carrying out combat operations. The decades that followed were marked by constant innovation, both in terms of the technology of production and transmission of toxic agents and the development of new doctrines for their application. We can observe the development of the doctrine on chemical weapons use in the 20th century. It began with the penetration doctrine in World War I; then progressed to hard suppression doctrine during the interwar period; the buffer doctrine during World War II; scorched earth doctrine; followed by rapid threat elimination doctrine after World War II. Finally, the last – doctrine to attract attention appeared at the end of the century. We can be sure that the 21st century will be marked by the development and implementation of new ones.

Bottom-line-up-front: From its first mass and systematic use in World War I through to the end of the 20th century, the use of chemical weapons can be observed through six phases. By observing the change in the purpose of using chemical weapons through these phases, we can derive six different doctrines explaining chemical weapons usage in the 20th century.

Problem statement: How did the systematic use of chemical weapons transform through time, following the change in the nature of human conflicts and subsequent scientific and technological development?

So what?: Considering the development and diversity of chemical weapons doctrine so far, it can certainly be expected that we will continue to witness the emergence of new ones. Various actors with different goals will apply them, and the international community should dedicate more time and effort to the subject.

Source: shutterstock.com/Everett Collection

The Use of toxic Chemical Substances in Warfare is Almost as Old as Warfare itself

Pepper (piperine – bio-active component of pepper)[1] and sulphur were the first substances used for disabling humans due to their chemical properties centuries before the common era. From the early development of chemical weapons, the most famous being the Chinese stinkpots and Greek fire, containing flammable mixtures including sulphur, were both introduced into use in naval battles.[2] The oldest known evidence of chemical attack comes from the battle at Dura-Europos, an ancient Roman city on the Euphrates River (modern-day Syria). In 2009, British archaeologists uncovered 20 Roman soldiers who died in battle with Persians in 256 AD after inhaling poison gas.[3] Nevertheless, until World War I, there was no systematic use of chemical weapons. World War I marked the period of its entry into mass use. The precondition for this was reached at the end of the 19th century, when the chemical industry experienced its rapid development. Almost all war poisons used in World War I were developed at that time. At that time resistance to the use of poisonous substances for war purposes also emerged. However, despite discussions led by some European governments about the morality of the use of certain types of weapons, the development of chemical weapons was not stopped. Work continued on the inventions and production of new war poisons and improvements of their translation into combat operations in the field.

However, despite discussions led by some European governments about the morality of the use of certain types of weapons, the development of chemical weapons was not stopped.

From its first mass and systematic use in World War I through to the end of the 20th century, the use of chemical weapons can be observed through six phases. By observing the change in the purpose of using chemical weapons through these phases, we can derive six different doctrines explaining chemical weapons usage in the 20th century.

The Penetration Doctrine

The first doctrine used was introduced to penetrate the enemy line and overcome the stalemate in trench warfare on the battlefields of World War I. On April 22, 1915, starting the Second Battle of Ypres, the German Army used 180,000 kg of chlorine, discharging it from the 6,000 steel bottles down trenches along the 6-kilometer-long front against French-Algerian and Canadian troops. It created a 6-kilometer hole in their front lines.[4] 15,000 soldiers were injured and 5,000 died in the attack.[5] The German side failed to take advantage of the unexpected psychological effect that the weapon had on its soldiers, which enabled the consolidation on the opposite side. It was the beginning of an era of mass and systematic use of chemical weapons. After this chemical attack, the use of toxic war agents became common on the western battlefield.

On September 25, 1915, the British side carried out their first chlorine attack on the German Army during the Battle of Loos. The attack was unsuccessful due to wind direction and difficulties in handling the equipment.[6] On the Eastern front, the German Army also used poison gas – xylyl bromide – on January 31, 1915, against the Russian Army, in the Battle of Bolimov. Again, the expected results were not achieved due to the ambiguous wind direction and low temperatures, which caused the gas to freeze instead of evaporating.[7]

On the Eastern front, the German Army also used poison gas – xylyl bromide – on January 31, 1915, against the Russian Army, in the Battle of Bolimov.

The most widely used toxic agent in World War I was phosgene, whose importance diminished only after discovering nerve war poisons. It is estimated that by 1918, poisonous gases had killed 100,000 people and injured more than a million people. 110,000 tons of chemical weapons were used.[8]

The number of casualties and unseen injuries caused by chemical weapons led to the signing of the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, in Geneva, 1925 (Geneva Gas Protocol). However, the development, production, possession and stockpiling of chemical and biological weapons was not covered within the Protocol.

A step further was made in Geneva 1993 by signing the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction (the Chemical Weapons Convention – CWC), and establishing International Organization for the Prohibition of Chemical Weapons, based in Hague.[9]

The Hard Suppression Doctrine

After World War I, chemical weapons were used by Britain, Russia, Spain, Italy, and Japan to suppress rebel forces. In the late summer of 1919, British air forces used the toxic gas Adamsite in their attacks on areas in northern Russia, in the villages near Archangel and Murmansk, held by the Red Army. It was assumed that the use of chemical weapons would bring fast results: instant victory over the Bolshevik regime. Expectations were not met due to the type of terrain (dense forest) and strong winds. Therefore, the results were local and limited. In September, the British Army ceased the attacks.[10] British use of chemical weapons in northern Russia was the first use of chemical weapons after World War I. It was the first application of chemical weapons carried out by the air force and the first case of a hard suppression doctrine aimed at suppressing the rebel forces – in this case, rebels looking through the prism of political ideology.

British use of chemical weapons in northern Russia was the first use of chemical weapons after World War I.

Two years later, in the summer of 1921, the Red Army also used chemical weapons – fighting the uprising peasants to suppress the Tambov rebellion. The Tambov rebellion began as a revolt of the local rural population against the central state authorities’ forced seizure of grain. It developed into a broader movement of expression of dissatisfaction with certain political decisions of the state leadership. The rebellion was successfully suppressed; most of the peasant forces were destroyed already in the summer, while the smaller groups continued to fight until the end of the year. Data from available sources do not allow accurate identification of the war poison type.[11]

In the 1920s, Spain engaged several chemical agents – chloropicrin, yperite, phosgene, and diphosgene – in Morocco against the Rif tribe in the north of the country. It was the first case of chemical weapons engagement to suppress anticolonial forces formed by the domicile population. The Rif tribe from a mountainous region in northern Morocco fought for five years, from 1921 until 1926, against a colonial power Spain, aided since May 1924 by French forces. The combined joined Spanish and French forces significantly exceeded the capacities of the Rif tribe in manpower and equipment, which decided the outcome of the conflict.[12]

The next decade was marked by Italian use of yperite in Abyssinia during the Second Italo-Abyssinian war (1935-1936) and in Libya[13] as well as the Japanese in China. Although the domestic population offered strong resistance, they could not match the Italian and Japanese forces.[14] Unfortunately in all six cases, the data on casualties caused by chemical weapons use is not available.

The Buffer Doctrine

During World War II, chemical weapons were not systematically used in Europe but were, for the first time, at least theoretically, they were incorporated in a broader defence strategy. In response to the possible German invasion of the United Kingdom in 1940, the British side developed plans, called Operation Sea Lion, that included using yperite at possible points of the enemy landing.[15] Although the idea of using parts of its own territory as a buffer zone by contamination with war poisons provoked severe debates in the highest circles, it was not abandoned. Since the operation was never been conducted, chemical weapons have not been tested for defensive purposes in real conditions.

Although the idea of using parts of its own territory as a buffer zone by contamination with war poisons provoked severe debates in the highest circles, it was not abandoned.

The Scorched Earth Doctrine

Various countries participated in the application of the first doctrines. However, in the development and implementation of scorched earth doctrine, only one country stands out – the United States of America. After World War II, in the 1950s and 1960s, the United States applied this doctrine in the wars in Korea (1951 – 1952) and Vietnam (1962 – 1971). During the Vietnam war, over an area of 20,000 km², more than 80 million liters of herbicides were used to destroy cereal plantations and for defoliation purposes. Known under the names “Agent Orange”, “Agent Purple”, “Agent Blue” and “Agent White”, they were employed by the air force for long-term destruction of the food capacity in an engagement area (even without the possibility of restoration), and for revealing of the position of forces on the ground. Besides the herbicides, there were used lachrymatory agents CS (2-chlorobenzalmalononitrile) and CR (dibenzoxazepine).[16]

During the Vietnam war, over an area of 20,000 km², more than 80 million liters of herbicides were used to destroy cereal plantations and for defoliation purposes. Known under the names “Agent Orange”, “Agent Purple”, “Agent Blue” and “Agent White”, they were employed by the air force for long-term destruction of the food capacity in an engagement area (even without the possibility of restoration), and for revealing of the position of forces on the ground.

The Rapid Threat Elimination Doctrine

Similar to the post-World War I period, the decades after World War II were marked by the localised use of chemical weapons of technologically superior forces over a party that was unable to find or apply an appropriate response. The goal was the rapid and thorough elimination of the threat, the immediate cessation of opposing forces in the context of a wider conflict. Although this doctrine showed results in the short term, it did not significantly influence the conflict’s outcome. The use was recorded in North Yemen, Rhodesia, Angola, Thailand, Iran and Iraq.

The scope and nature of the target group can vary considerably – from smaller or larger groups within their own country (Rhodesia, Iraq), through smaller or larger groups within foreign countries (Egypt in North Yemen, Cuba in Angola, Vietnam in Thailand), to entire foreign countries (Iraq in Iran). Between 1963 and 1967, Egypt used yperite and phosgene against royalist forces in North Yemen during the civil war. Chemical weapons are estimated to have caused about 1,500 deaths and an equal number of injuries.

Between 1963 and 1967, Egypt used yperite and phosgene against royalist forces in North Yemen during the civil war.

In the second half of the 1970s, governmental forces used organophosphates and thallium against Rhodesian rebels, resulting in 1,000 deaths. In the 1980s, chemical weapons were used in Angola by Cuba during the Cuban intervention and in Thailand by Vietnam. However, the most infamous was the Iraqi use of yperite and tabun against Iranians and yperite tabun, sarin and VX against the Kurdish population in Halabja. The Iranian side suffered 20,000 losses and 5,000 injured, and the Kurdish side had between 3,200 and 5,000 losses and between 7,000 and 10,000 injured.[17]

The Attracting Attention Doctrine

The end of the century brought up a new doctrine for chemical weapons – the use of chemical agents by smaller groups against a general civilian population. On June 27, 1994, the apocalyptic Japanese group Aum Shinrikyo released sarin in Matsumoto, killing eight and injuring more than 200 persons. The following year, they caused 12 deaths and over 5,000 injuries by releasing sarin into the Tokyo subway.

Although there is no precise data, we can assume that the group desired to draw public attention to its goal of “teaching the truth about the origin and destruction of the world”.[18] The group still exists today under the names Aleph and Hikari no Wa.[19]

The 20th century was marked by doctrinal diversity in the use of chemical weapons. Since the first mass and systematic application of war poisons during World War I, their vast possibilities in conducting combat operations have been recognised. Numerous innovations in the technology of transmission of war poisons followed and efforts to discover new toxic substances. In accordance with these changes, but also in changes in the nature of conflicts, doctrines also adapted.

Since the first mass and systematic application of war poisons during World War I, their vast possibilities in conducting combat operations have been recognised.

Based on experiences of the 20th century and observing the direction of development of international relations, in the 21st century, we can expect the further application of toxic chemicals against a general civilian population and localised application in intra- and inter-state conflicts. The actors developing new doctrines will vary from the smaller groups, non-state actors to the whole countries. The international community will face the challenge of finding answers to a wide range of threats.


Natalija Lukec, University Specialist in National Security, Master of Arts in Political Science: National Security, International Politics and Diplomacy, Zagreb, Croatia. Mensa member. Research fields: Building a European Security Architecture; The Geopolitics of the Middle East; Hybrid Warfare; Weapons of Mass Destruction; Systems Theory in Political Science. The views contained in this article are the author’s alone.


[1] “Piperine – Toxicological Information”, National Library of Medicine, National Center for Biotechnology Information, Bethesda, USA, accessed July 5, 2021, https://pubchem.ncbi.nlm.nih.gov/compound/Piperine#section=Toxicological-Information, accessed August 4, 2021.

[2] Slavko Bokan, Ankica Čižmek, Boris Ilijaš, Ivan Jukić, Zvonko Orehovec, Željko, Radalj, Oružja za masovno uništavanje: nuklearno-kemijsko-biološko I toksinsko oružje (Zagreb: Pučko otvoreno učilište, 2004), 203-209, 225-226.

[3] “Gas Warfare at Dura-Europos”, published November 7, 2009, accessed July 19, 2021, Current World Archaeology, https://www.world-archaeology.com/features/gas-warfare-at-dura-europos/.

[4] R.H. Roy, and Richard Foot. “Canada and the Second Battle of Ypres”, published July 27, 2006, last edited December 4, 2018, The Canadian Encyclopedia, accessed July 2, 2021, https://www.thecanadianencyclopedia.ca/en/article/battle-of-ypres/.

[5] Slavko Bokan et al., Oružja za masovno uništavanje, 203-209, 225-226.

[6] “Bataille de Loos – Septembre 1915.”, Loos, sur les traces de la Grande Guerre, Musée Alexandre Villedieu, Loos en Gohelle, accessed July 5, 2021, https://www.loos1915.fr/deuxieme-bataille-de-loos.

[7] J. Rickard. “Battle of Bolimov, 31. January 1915”, published August 28, 2007, Military History Encyclopedia on the Web, accessed July 7, 2021, http://www.historyofwar.org/articles/battles_bolimov.html.

[8] Slavko Bokan et al., Oružja za masovno uništavanje, 203-209, 225-226.

[9] The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction, Organisation for the Prohibition of Chemical Weapons, accessed August 2, 2021, https://www.opcw.org/chemical-weapons-convention.

[10] Simon Jones. “When Chemical Weapons Were First Dropped from the Air, North Russia 1919”, Imperial War Museum Review, No. 12, 1999, accessed July 9, 2021, https://simonjoneshistorian.com/2015/03/02/when-chemical-weapons-were-first-dropped-from-the-air-north-russia-1919/.

[11] Lev Aleksandrovich Fedorov Moscow. Chemical Weapons in Russia: History, Ecology, Politics [Khimicheskoye Oruzhiye V Rossii: Istoriya, Ekologiya, Politika], Center of Ecological Policy of Russia, published on July 27, 1994, accessed July 22, 2021, https://fas.org/nuke/guide/russia/cbw/jptac008_l94001.htm.

[12] Robert Miller. War Crimes: Spanish Use of Chemical Weapons in Northern Morocco still Causing Suffering, Gilmore Health News, published on June 20, 2021, accessed July 12, 2021, https://www.gilmorehealth.com/war-crimes-spanish-use-of-chemical-weapons-in-northern-morocco-still-causing-suffering/.

[13] Lina Grip and John Hart. “The use of the chemical weapons in the 1935-36 Italo-Ethiopian War”, SIPRI Arms Control and Non-proliferation Programme, October 2009, accessed July 14, 2021, https://www.sipri.org/sites/default/files/Italo-Ethiopian-war.pdf.

[14] Justin McCurry. “Unit 731: Japan discloses details of notorious chemical warfare division, April 17, 2018, The Guardian, accessed on July 15, 2021, https://www.theguardian.com/world/2018/apr/17/japan-unit-731-imperial-army-second-world-war.

[15] Leo McKinstry. “Britain’s fight for survival: Fortress Britain 1940”, History Extra, the official website for BBC History Magazine and BBC History Revealed, accessed July 2, 2021, https://www.historyextra.com/period/second-world-war/britains-fight-for-survival-fortress-britain-1940/.

[16] Slavko Bokan et al., Oružja za masovno uništavanje, 203-209, 225-226.

[17] “Chemical weapon”, Encyclopaedia Britannica, accessed August 2, 2021, https://www.britannica.com/technology/chemical-weapon.

[18] Lloyd Pettiford and David Harding, Terorizam: novi svjetski rat, trans. Damir Biličić (Zagreb: Mozaik knjiga, 2005), 109-110.

[19] Matthew Hernon. False sense of security? Experts weigh the threat that terrorism poses Japan, The Japan Times, published on March 18 2017, accessed July 27,2021 https://www.japantimes.co.jp/tag/hikari-no-wa/.

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