Germany Uses Poison Gas Against Allied Troops

In the Second Battle of Ypres, the German army introduced the widespread use of poison gas to end the deadlock of trench warfare in World War I. In spite of the panic that was initially created, determined Allied soldiers slowed the German advance and reconstituted the line. Although this battle did not result in a breakthrough, it introduced a horror that would affect battles throughout the war and enhance antiwar sentiment in the postwar years.

Summary of Event

The opening campaigns of World War I in 1914 saw horrendous losses inflicted by quick-firing artillery and machine guns. Soldiers sought protection from fire in elaborate trench networks, but attacks on the trenches resulted in heavy casualties. In response, both sides investigated the possibility of technological solutions, including the use of gas. In February of 1915, the French unsuccessfully tried to use ethyl bromo-acetate (a type of tear gas) in special projectiles fired by rifles. World War I (1914-1918)[World War 01];Second Battle of Ypres[Ypres, Second Battle]
Ypres, Second Battle of (1915)
Chemical weapons
Weapons;chemical and bacteriological
[kw]Germany Uses Poison Gas Against Allied Troops (Apr. 22-27, 1915)
[kw]Poison Gas Against Allied Troops, Germany Uses (Apr. 22-27, 1915)
[kw]Gas Against Allied Troops, Germany Uses Poison (Apr. 22-27, 1915)
[kw]Allied Troops, Germany Uses Poison Gas Against (Apr. 22-27, 1915)
[kw]Troops, Germany Uses Poison Gas Against Allied (Apr. 22-27, 1915)
World War I (1914-1918)[World War 01];Second Battle of Ypres[Ypres, Second Battle]
Ypres, Second Battle of (1915)
Chemical weapons
Weapons;chemical and bacteriological
[g]Germany;Apr. 22-27, 1915: Germany Uses Poison Gas Against Allied Troops[03750]
[c]World War I;Apr. 22-27, 1915: Germany Uses Poison Gas Against Allied Troops[03750]
[c]Military history;Apr. 22-27, 1915: Germany Uses Poison Gas Against Allied Troops[03750]
[c]Wars, uprisings, and civil unrest;Apr. 22-27, 1915: Germany Uses Poison Gas Against Allied Troops[03750]
[c]Atrocities and war crimes;Apr. 22-27, 1915: Germany Uses Poison Gas Against Allied Troops[03750]
Haber, Fritz
Falkenhayn, Erich von
Albert, duke of Württemberg
Foch, Ferdinand

German research into gas use began in the fall of 1914. From September 5 to 9, 1914, the German army had fought and was ultimately defeated in the First Battle of the Marne. In response, the new chief of the general staff, General Erich von Falkenhayn, authorized the use of gas. Early German efforts to employ chemical weapons were disappointing, however. The first attempts used a form of sneezing powder; when that failed, attention turned to another form of tear gas, xylyl bromide, which was delivered by artillery shells. Xylyl bromide was used in Russia at the Battle of Bolimov in January of 1915, Bolimov, Battle of (1915) but the extreme cold prevented the gas from spreading. Most of the Russian troops in the battle did not even realize they had been gassed.

Dr. Fritz Haber, a German scientist, understood that special shells might be fragile as well as difficult to design, build, and produce. Instead of shells, Haber recommended that canisters be used to release chlorine gas. Germany’s chemical industry was the world’s largest, and chlorine already had industrial applications, so it was easily turned into a weapon. However, Haber’s contribution to the German war effort was not limited to the use of canisters or the selection of chlorine gas: He was the first to propose the use of gas as a method of overwhelming opposing forces. His delivery system was flawed, however, because it meant that gas could be used as a weapon only when winds blew in the correct direction, and on the western front prevailing winds blew toward German positions.

Many German generals opposed the idea of gas warfare, since the 1896 Hague Peace Conference had banned the use of “asphyxiating and deleterious gasses.” Haber and others justified their work as a response to France’s unsuccessful efforts to develop a poisonous gas, and they also argued that gas would save lives by ending the war. Duke Albert of Württemberg was willing to use gas, and so Falkenhayn ordered the new weapon to be tested in Albert’s area, which included the Ypres salient, thirty miles southwest of Bruges, Belgium. Since Falkenhayn had ordered a gas attack as an experiment, attack plans focused on testing rather than on opening the front. Like the much-heralded British misuse of a small number of tanks in 1916, Falkenhayn’s decision would waste a golden opportunity.

Canisters were placed near British trenches in March of 1915, but consistently poor wind conditions delayed the attack until April. By late April, the attack had been relocated from the eastern face of the salient to its northern face, where the winds were more reliable. Here the Allied positions amplified German advantages. Ypres was a juncture of Belgian, French, and British units, and coordination among these armies remained poor throughout the battle. The ground’s flat, waterlogged condition made trench life miserable, and maintaining continuous trench lines was unrealistic. As a result, many positions were scattered, fortified posts rather than trenches.

Germany’s position was further strengthened by the fact that the enemy’s forces were relatively inexperienced. French positions were manned by the Forty-fifth Division, which consisted of troops from France’s African colonies, and the Eighteenth Division, which was largely composed of overage draftees. Most of the British troops were from the First Canadian Division, which had its first combat experience at Ypres. Because of the repeated weather delays, the German reserves originally slated for the offensive were shipped east to reinforce operations in Russia, which meant that the Ypres attack was effectively unsupported.

Wind conditions remained a crucial factor in the operation’s timing: The attack ordered for the morning of April 22, 1915, was delayed until 5:00 p.m., when the wind finally blew in the correct direction. The use of gas took the Allies by surprise, despite several warnings that such an attack was planned. Air reconnaissance had noted the emplacement of the canisters, and two disgruntled German deserters had surrendered, warned of the impending attack, and even shown their primitive gas masks—gauze face masks impregnated with a chemical to negate the gas—to no effect. French generals discounted these reports, and the troops were not warned.

When attackers released more than four hundred tons of gas from fifty-seven hundred canisters, the resultant gas cloud was nearly four miles wide, fifty feet high, and hundreds of yards deep. In response, France’s Eighteenth Division disintegrated, while many men in the Forty-fifth Division scattered. German troops followed the retreating French forces, and in the process the Germans were able to destroy a great deal of the Eighteenth Division’s artillery. After the first day of battle, French forces had been largely stripped of their weapons and had to depend on neighboring units for fire support.

As soldiers fell, a mile-wide gap opened in the Allied line. The Germans, however, failed to exploit this opportunity. This was partially the result of the tenacity shown by the many French soldiers who continued to fight, even as they inhaled the gas, as well as the ferocity of the better-organized Canadians, whose good fortune saw the gas cloud blow past rather than into their positions. The limited German advance was also the result of that army’s tepid expectations. Neither Falkenhayn nor Albert really expected a breakthrough, so subordinates were not ordered to rush into the gap as soon as it appeared. As darkness fell, the Germans consolidated their gains rather than exploit the breach, and by midnight, they had constructed entrenchments against anticipated Allied counterattacks.

This pause gave the Canadians and French time to shift troops and launch counterattacks. The first of these began at midnight on April 22, when the Canadians marched into the line. There had not been time for preattack reconnaissance, and the result was a bloodbath: The two Canadian battalions suffered nearly 75 percent casualties. Subsequent German advances grew more cautious, however. Furthermore, as the Allied generals began to recognize the scope of the German penetration, they planned other counterattacks.

France’s representative in this area was General Ferdinand Foch, who promised French counterattacks before receiving accurate information about the conditions in the salient and the disintegration of the two French divisions. Ferocious attacks by the Canadians and grim defensive battles fought by small groups of intermixed Canadian and French stragglers inflicted heavy German casualties, and the limited German forces were ultimately exhausted. German officers had anticipated neither the sudden breakthrough nor the subsequent heavy resistance, and they were unable to sustain the fighting. By April 27, the breach had been sealed, and the rest of the battle—which most scholars date from April 22 to May 25, 1915—devolved into a contest of attrition.

By the battle’s end, thirty-five thousand Germans, sixty thousand British and Canadians, and ten thousand French soldiers had been killed. Most of the deaths were caused by artillery and machine gun fire, however, not by gas. It is believed that approximately three thousand British and Canadians—a relatively small percentage of total deaths—were killed by gas at Ypres. Still, the use of chlorine gas had considerable impact on morale, and the Allies quickly developed their own gas weapons in response. Building gas weapons and respirators was relatively simple, and the winds moved in the Allies’ favor. As a result, by war’s end, the Germans had launched just 24 gas attacks and had been the targets of more than 170 gas attacks by the British, French, and Americans. Clearly, the introduction of gas warfare harmed the Germans far more than it helped them.


The surprise German gas attack near Ypres was the war’s first successful application of gas warfare. Although the attack at Ypres initially caused many troops to panic and briefly tore a hole in the Allied defenses, the Germans were unable to exploit the temporary advantage created by their use of gas. Courageous counterattacks blunted German movements, and by the second day the Allies had improvised masks that reduced the effectiveness of the chlorine gas. Furthermore, the short-term German gain in one battle in no way balanced the terror and misery that gas weapons inflicted throughout the remainder of the war. Once the Germans had introduced poison gas, the Allies quickly manufactured their own and inflicted great damage on the German troops. Although a relatively small proportion of deaths among soldiers were the result of gas exposure, the rates of death and injury from the use of chemical weapons was high enough to have a strong impact on morale. When World War I ended, negative feelings about gas attacks helped to fuel a loud and sometimes effective antiwar movement that helped shape interwar politics and diplomacy. World War I (1914-1918)[World War 01];Second Battle of Ypres[Ypres, Second Battle]
Ypres, Second Battle of (1915)
Chemical weapons
Weapons;chemical and bacteriological

Further Reading

  • Brown, Frederick J. Chemical Warfare: A Study in Restraints. 1968. Reprint. New Brunswick, N.J.: Transaction, 2005. Account of the history of the use of chemical weapons and attempts to restrain use by legal measures. Also discusses the “humanity” of chemical warfare. Includes important material about chemical warfare and chemical arms control that is difficult to find elsewhere.
  • Charles, Daniel. Master Mind: The Rise and Fall of Fritz Haber, the Nobel Laureate Who Launched the Age of Chemical Warfare. New York: HarperCollins, 2005. Full-scale biography of the scientist who led the German chemical weapons effort during World War I. Places Haber’s work in the context of his times. Includes bibliography and index.
  • Christie, N. M. Gas Attack! The Canadians at Ypres, 1915. Nepean, Ont.: CEF Books, 1998. Although focused on the Canadians, this presents a balanced view of the battle and features many firsthand accounts from survivors.
  • Coleman, Kim. A History of Chemical Warfare. New York: Palgrave Macmillan, 2005. Describes the development and use of chemical weapons from 700 b.c.e. to the beginning of the twenty-first century, with extensive discussion of World War I. Also assesses current attempts to control the use and proliferation of such weapons and analyzes their potential use by terrorist groups.
  • Fotion, Nicholas G., and Gerard Elfstrom. “Weapons of War.” In Military Ethics: Guidelines for Peace and War. Boston: Routledge & Kegan Paul, 1986. Interesting and persuasive utilitarian argument for why use of some kinds of weapons, including chemical and biological weapons, ought to be morally condemned whereas use of others is permissible. Distinguishes between first use and retaliation.
  • Groom, Winston. A Storm in Flanders: The Ypres Salient, 1914-1918. New York: Atlantic Monthly Press, 2002. This is a very accessible overview of all of the battles at Ypres, including the Second Battle of Ypres in April, 1915.
  • Haber, L. F. The Poisonous Cloud: Chemical Warfare in the First World War. New York: Oxford University Press, 1986. A painstaking and thorough account of the origins, development, organization, use, and effects of chemical weapons in World War I. Written by the son of chemist Fritz Haber, who presided over the German chemical weapons program. Some of the conclusions are controversial, but this book should not be missed by anyone interested in the history of chemical warfare.
  • Hart, Liddell. History of the First World War. London: Palgrave Macmillan, 1982. Originally published in 1930 under the title The Real War, 1914-1918, this book provides a readable and detailed account of World War I that manages to capture not only successes and failures of strategy on the grand level but also a good deal of the flavor of what it was like to live through the events chronicled. Provides a good background for understanding chemical warfare in the context of World War I.
  • McWilliams, James L. Gas! The Battle for Ypres, 1915. St. Catharine’s, Ont.: Vanwell, 1985. This is an excellent study of the details of the battle. Its balanced treatment of the French and Belgian contributions to victory is especially impressive.
  • Richter, Donald C. Chemical Soldiers: British Gas Warfare in World War I. Lawrence: University Press of Kansas, 1992. Presents a detailed, scholarly look at the use of chemical weapons during World War I from the perspective of the British military brigade instituted to combat the Germans’ use of chemicals. Includes maps, appendixes, and bibliography.
  • Spiers, Edward M. Chemical Warfare. Chicago: University of Illinois Press, 1986. A useful account of the modern history of chemical warfare and chemical arms control, now somewhat dated by the fact that it was written before the 1988 chemical weapons offensives by Iraq.
  • Stockholm International Peace Research Institute. The Rise of CB Weapons. Vol. 1 in The Problem of Chemical and Biological Warfare. New York: Humanities Press, 1971. Part of a series that constitutes the definitive account of chemical and biological weapons before the 1970’s. Provides an overview and covers the history of chemical weapons and warfare from 1914 to 1970 and also evaluates more than two hundred alleged uses. Both comprehensive and carefully objective in approach.

Second Hague Peace Conference

Outbreak of World War I

World War I

First Battle of the Marne

United States Enters World War I

Geneva Protocol Is Signed