Last modified on September 26, 2018, at 19:12

Poison gas

Poison gas was the most controversial weapon of World War I—indeed, next to nuclear weapons, the most controversial weapon of the 20th century. Its strange history reveals much about how generals, privates, politicians and civilians understood total war.

Poison gas was easily neutralized by gas masks, and was highly unpredictable (because of wind and weather). It never helped win a major battle. The soldiers hated it intensely, and the generals soon decided it was more trouble than it was worth. The most famous gas artillery officer of the war was U.S. Army Captain Harry S. Truman, who later became president; the most famous victim was Adolf Hitler, who was gassed twice.

Relatively few soldiers were killed and not many were permanently injured. By far the major killer was conventional artillery, along with machine guns. Gas however had a hypnotic effect—many soldiers saw their comrades falling and thought they smelled some odor—it must be gas, and they too collapsed, even though there was no gas present.


Germany dominated the world's young chemical industry. Chlorine was an important industrial chemical; the technology to manufacture and store large quantities was well known. In 1899 the Hague Peace Conference outlawed "asphyxiating or deleterious gases." Ignoring the prohibition, German chemists, led by Nobel-prize winner Fritz Haber, promised that chlorine could break the stalemate in the trenches.

First use, 1915

The first attack came at St. Julien, during the Second Battle of Ypres on the night of 21–22 April 1915, as Germans opened thousands of cylinders and waited for the wind to carry it into the Allied lines. Two French divisions (the 45th Algerian and 78th Territorial) fled in panic. Astonished by the results the new weapon achieved, the Germans were unprepared to take advantage and advanced slowly into the four mile gap in the line. The Canadian Division was hastily assembled and counter-attacked, restoring the front over the course of several days, at the cost of about half the division.

Gas mask or death

Within three days Allied doctors had developed a simple but adequate mask and shipped 200,000 to the front; air that was breathed through ordinary washing soda was safe. By 1916 the British soldiers carried an excellent rubber face mask with glass eyepieces and a tube connecting it to a separate respirators. The new masks gave practically 100% protection—but only when they were worn. The Russians never obtained an adequate supply, and suffered hundreds of thousands of casualties. Death came in a matter of days, due to asphyxia or lack of oxygen—the lungs filled up with fluids and the victims drowned in their own secretions. One effective treatment was venesection: surgeons cut a vein and pumped out 20- 25 ounces of blood.

Allied usage

Although the Allies vigorously denounced poison gas as a heinous crime—a cruel trick on hapless soldiers already living in hell—they rushed to make their own gas. The Americans, at peace, ignored the new weapon. Release by cylinders proved unwieldy and dangerous, for it depended on just the right atmospheric conditions; sudden wind changes could backfire for the attackers. By 1916 the belligerents turned to artillery shells, each of which could land a few pounds of liquefied poisons on precise targets far behind the trenches, especially enemy artillery parks and communication posts that had been spotted by airplane. Usually gas shells and high explosive shells were mixed together in an attack. On the front lines gas was a harassment but not a tactical factor. A huge amount of gas had to be released in a small area in a short period in order to be effective, yet the same amount of high explosive would do much more damage.

Phosgene and mustard gas

Chemists invented 18 new gases that were more deadly effective than chlorine, and also masks to neutralize them. Phosgene ("Green Cross", the Germans called it) like chlorine, attacked the lungs, only more quickly—without a mask a victim had one minute to live—but it evaporated in 30 minutes.

WW2 US Army poster

The Germans introduced mustard gas ("Yellow Cross") in July, 1917. While not a killer, it caused severe blisters in the lungs and on exposed skin that could temporarily blind or incapacitate for weeks or months. Mustard gas (actually a liquid) did not evaporate, so elaborate decontamination routines were necessary to wash off humans, equipment and terrain. Late in the war, Berlin invented arsenic compounds ("Blue Cross") which, while not lethal, caused uncontrollable sneezing or nausea that forced victims to remove their masks, thus exposing them to lethal gases. (Nerve gases were not invented until the 1930s.)


Three percent of all casualties on the Western Front were attributed to gas; 1,200 Americans died from it. Far larger numbers were reported as casualties, but many of the cases were dubious. Both sides mixed gas shells with high explosives, and Doughboys who kept their heads down were never quite sure if they had been gassed. Only 20% of soldiers treated for mustard gas were kept in bed more than 48 hours. British statistics indicate that one in thirty-eight of the casualties from `mustard gas' died and about one in four hundred was incapacitated for six months or longer.[1] Seriously affected patients required elaborate nursing care and extended bed rest to avoid the danger of pneumonia; over 90% eventually recovered. Gas was, however, a debilitating psychological weapon. Soldiers hated the masks because of the claustrophobia, the difficulty in getting enough oxygen for strenuous movement, and the garbling of voices and commands. By 1918 the constant fear, and the continuous use of those awful masks, was a major contributor to combat fatigue—a psychological condition in which the soldier loses control of his emotions and was a liability in combat. Poison gas never won a battle. By forcing soldiers to wear their masks, it, did however, slow down the tempo of operations, made coordination difficult, ruin morale, and increase the vulnerability of soldiers to artillery and machine 25 gun fire. Germany favored gas because it was on the defensive on the Western Front from late 1914 to early 1918, and its large, sophisticated chemical industry delivered a high quality product. Germany and Austria fired 58% of the 66 million gas shells used in the war, but with smaller steel industries, only 47% of the 1.4 billion high explosive shells. The most famous victim of gas was German corporal Adolf Hitler, hit by mustard gas in October, 1918.

"Gassed" (1919) by American artist John Singer Sargent, after visiting the front[2]

No battle was decided by the use of poison gas, and the number of actual casualties inflicted was a tiny fraction of the overall number.[3]

Banning gas in 1920s

After years of agitation by women's groups in Europe and the U.S. (led by Jane Addams). the 1925 Geneva protocol banned poison gas as an illegal weapon of mass destruction.[4] Nevertheless, in the pacifistic decade of the 1920s, dire predictions struck fear worldwide that the next war would see long-range bombers gassing millions of civilians in the large cities. Technologically that was quite impossible (it would take hundreds of thousands of bomber sorties to gas New York City or London), but the fears presaged the nightmares in the 1960s about nuclear weapons that were all too realistic. Apart from chemists who insisted that gas was far more humane than high explosives, the military did not want chemical warfare. It therefore acquiesced in the international consensus reached in the 1920s that poison gas was an illegal and immoral weapon of mass destruction. Nations pledged never to use it first—but they nevertheless prepared masks and their own stocks of poison in case they needed to retaliate. Since 1918 gas has occasionally been used in remote areas against civilians or soldiers with no protection. (Washington vehemently denies undocumented allegations that it ever used poison gas, nerve gas, or biological weapons in Korea or Vietnam or anywhere else.) Since 1918, no nation has used poison gas against a foe that had masks or gas of its own.[5] During World War II the Nazis experimented with killings using carbon monoxide, but switched to a special purpose poison called Zyklon B, the poison gas used to murder millions of Jews in the Holocaust.

Nevertheless, poison gas still strikes fear—as evidenced in the Gulf War of 1991, when no gas was in fact used. In World War II, the major armies had large supplies of poison gas ready to retaliate in case the other side used it, but were very reluctant to use it under any circumstances.[6] When one local Polish unit used mustard gas against the Nazi invaders in 1939, the Germans did not retaliate. The Allies deliberately ignored Japanese use of gas against China and Italian use against Ethiopia.[7]

Further reading

  • Fries, Amos Alfred, and Clarence Jay West. Chemical Warfare (1921) 445 pages online edition
  • Haber, L. F. The Poisonous Cloud: Chemical Warfare in the First World War (1986), the standard scholarly history, by the son of the main inventor
  • Slotten, Hugh R. "Humane Chemistry or Scientific Barbarism? American Responses to World War I Poison Gas, 1915-1930." Journal of American History 1990 77(2): 476-498. Issn: 0021-8723 Fulltext: in Jstor
  • Trumpener, Ulrich. "The Road to Ypres: the Beginnings of Gas Warfare in World War I." Journal of Modern History 1975 47(3): 460-480. Issn: 0022-2801 Fulltext: in Jstor


  1. Oxford English Dictionary, Discovery 1934 Feb. 32/1
  2. For commentary on the paining, see Geoff Dyer on "Gassed" at
  3. Holmes, Richard Tommy: The British Soldier on the Western Front
  4. Allison Sobek, "How Did the Women's International League for Peace and Freedom Campaign Against Chemical Warfare, 1915-1930?" Women and Social Movements in the United States, 1600-2000 (2001) #5; Cook (2000)
  5. Italy used mustard gas in Ethiopia in 1935.
  6. On December 2, 1943, German warplanes bombed an American transport ship in the harbor of Bari, Italy, that contained canisters of mustard gas. The gas was released and killed 1000 Allied soldiers and more a thousand civilians. Gerald Reminick, Nightmare in Bari: The World War II Liberty Ship Poison Gas Disaster and Coverup 2001.
  7. Jeffrey W. Legro, "Military Culture and Inadvertent Escalation in World War II." International Security, Vol. 18, No. 4 (Spring, 1994), pp. 108-142 in JSTOR