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Militarization of Chemistry: World War I and Fritz Haber

Written by Sarya Gulec

Among the weapons of mass destruction, chemical weapons stand out as the most brutal compared to biological and nuclear weapons. They are cheaper and easier to produce by even small terrorist groups and can cause mass death with small quantities.

The Beginning of Chemical Warfare

While it is recognized that chemicals being used at wars and conflicts, generally they were used for their flammable, rather than toxic properties. The first reported usage of chemicals as a weapon due to their toxic properties occurred in the year 256 BC, during the siege of the Persian city Dura Europos (modern Syria) where they used a mixture of tar and sulfur to produce sulfur oxides and thus take control of the city.

The first large-scale use of a traditional weapon of mass destruction (chemical, biological, or nuclear) involved the successful deployment of chemical weapons during World War I (1914–1918).(2)  Because of the scientific and engineering mobilization efforts by the major belligerents historians sometimes refer to the Great War as the chemist’s war. 

Although, loss of soldiers were proportionally few in World War I, the psychological damage from “gas fright” and the exposure of large numbers of soldiers, munitions workers, and civilians to chemical agents had significant public health consequences.

Chemical Weapons at World War I

While it is believed that Germany was first to use chemicals in World War I, it was actually France who first launched bromyl ethyl acetate tear gas grenades in August 1914. Germans who were aware of the interest in developing chemical weapons also focused on their chemical industry. 

In the late afternoon of  April 22, 1915 at Ypres, Belgium, members of a special unit in the German army opened the valves and launched nearly 170 tons of chlorine gas in more than 6000 steel cylinders. German military meteorologists who studied the area's prevailing wind patterns were trusted to give order to release the gas. Within a matter of minutes, this slow moving wall of gas killed more than 1000 French and Algerian soldiers, while wounding approximately 4000 more.(2) 

World War I ended with 1.3 million casualties due to chemical weapons, including 90,000 to 100,000 fatalities, primarily from phosgene.

Most chemical weapon casualties were caused by three substances: chlorine, phosgene, and mustard gas. 

Chlorine gas smells like bleach and produces a greenish yellow cloud. Chlorine gas immediately irritates the eyes, nose, lungs, and throat of those exposed to it and high doses cause asphyxiation. 

Phosgene smells like moldy hay and is six times more deadly than chlorine. It is a more practical weapon because it’s colorless, and soldiers will not know that they received a fatal dose.  After a day or two, victims’ lungs would fill with fluid, and they would slowly suffocate in an agonizing death.(1) During World War I, phosgene caused 85% of chemical weapon fatalities. 

Mustard gas is a potent blistering agent whose effects are not immediate. It has a strong smell like garlic, gasoline, rubber, or dead horses. Hours after the exposure, victims' eyes become bloodshot, begin to water, and become increasingly painful, with some victims suffering temporary blindness. To make things worse, the skin becomes blister, especially in the moist areas. Mustard gas is dubbed as The King of Battle Gases.

In total, the use of toxic chemicals including phosgene, sulfur mustard and lewisites caused 100,000 deaths.

Fritz Haber

Although, throughout history, lots of scientists helped and developed chemical weapons used his considerable intelligence to militarize chemistry in World War I. In April 1915 at Ypres,  he witnessed the first results of his labor. He defended such weapons are more humane than modern artillery until his death in 1934. 

After World War I allies considered Haber as a war criminal for his work. He remained unseen in Switzerland until his name was removed from the wanted list. After World War I, Haber helped improve a one-step process for making mustard gas; aided Russia in developing its first chemical-weapons plant by recommending a colleague to Russian emissaries looking for advice; and until 1933 cooperated with the German military in its secret chemical-weapon armament and research program, in direct contravention of the peace treaty signed in 1919.(1)

Despite all this, Haber’s work has also deeply benefited humankind. His discovery of the Haber-Bosch reaction underpinned the green revolution: strategy for synthesizing ammonia (which won the Nobel Prize in chemistry) paved for inexpensive fertilizers, with enormous benefits to agriculture. Fritz Haber also helped lay the foundations of 20th century electrochemistry and physical chemistry. In 1934 he died of a heart attack in Basel.


  1. Everts S. (2023, June 2). A brief history of chemical war. Science History Institute.

  2. Fitzgerald, G. J. (2008, April). Chemical Warfare and Medical Response During World War I. American Journal of Public Health.

  3. Ganesan K., Raza, S. K., & Vijayaraghavan, R. (2010). Chemical warfare agents. PubMed Central (PMC).

  4. Vilches D., Alburquerque, G., & Ramirez-Tagle, R. (2016, July). One hundred and one years after a milestone: Modern chemical weapons and World War ICiento un años después de un hito: las armas químicas y la Primera Guerra Mundial. Science Direct.


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