In the interwar period, the major powers discussed outlawing the use of poison gas, but they also continued to produce it. Prior to World War II, more than 40 nations signed the Geneva Protocol of 1925 banning the offensive use of chemical weapons in warfare. All of the main combatants in World War II save the United States and Japan ratified the protocol, which went into force in August 1928. Although the United States had first proposed the treaty, isolationist sentiment blocked its ratification in the Senate. Japan feared giving away any advantage in case of a conflict with the far more populous China. The signatory powers, however, reserved the right to utilize chemical weapons in a retaliatory attack and to employ them against a country that had not signed the protocol.
Chemical weapons are categorized by their effects on human beings, animals, and plants. Lung irritants, such as phosgene, make victims choke or suffocate, with symptoms usually delayed for several hours after contact. Vesicants, such as mustard gas, cause the skin to blister and the eyes to swell, sometimes with loss of sight. The symptoms of vesicants can be delayed up to 48 hours. Lacrimators are tear gases, such as chloracetophenone and brombenzylcyanide, which irritate the eyes and cause difficulty with breathing.
The warring powers also produced irritant smoke (such as sneezing gases or adamsite), screening smokes, and incendiaries. A new and very deadly chemical agent, nerve gas, was developed during the war. Nerve gases take effect quickly, producing symptoms in 10 to 30 minutes, depending on whether they are inhaled or absorbed through the skin.
Chemical weapons can be launched in a variety of forms: through shells and bombs that explode and disperse the chemicals into the air in drops or small particles, from containers with vaporized solids that infiltrate the air as a smoke, and through liquids released from airplanes as drops or mist. Chemical weapons can be more useful than conventional weapons, since their effects are longer lasting, sometimes persisting for days or weeks. The most desirable chemical agents have many of the same characteristics in common. They are effective in small concentrations, difficult to protect against, quickly and cheaply manufactured, made from easily obtainable raw materials, heavier than air, easily and safely transportable, effective against multiple parts of the body, and not easily detectable.
Three of the most common means used to deploy chemical agents by the end of World War I were the portable gas cylinder, the Livens Projector, and the chemical mortar. But these delivery systems were obsolete by the time of World War II, given the greater mobility of infantry troops. Accordingly, the size of chemical mortars was increased as was their range (to 1,400 yards), and the Livens Projector was replaced by 100 mm caliber, mobile rocket launchers. During the interwar years, governments also experimented with using airplanes to deliver chemical weapons, through cluster bombs and spraying. By the time World War II began, aerial bombardment with chemical weapons was the most common deployment mechanism. It is also possible to deploy chemical weapons, particularly mustard gas, in land mines and grenades. German leaders debated the feasibility of combining missiles and chemical weapons, but production of such mechanisms did not occur.
In stark contrast to the situation in World War I, chemical weapons were used only sparingly in World War II. The major powers were reluctant to employ them. This was, in part, because they were convinced that their opponents had extensive stockpiles of poison gases and because their own populations were not adequately prepared to withstand a retaliatory attack. They also did not wish to be the first to violate the Geneva Protocol. Several key leaders were hesitant to authorize the use of chemical weapons. Adolf Hitler, who had been gassed at Ypres in 1918, had a strong aversion to the use of gas as an offensive weapon, and President Franklin D. Roosevelt also opposed the use of chemical weapons. For the European powers in particular, the threat of retribution against cities and large-scale civilian suffering was a major deterrent. The shipping of chemical weapons and equipping friendly troops for chemical attacks also presented logistical difficulties. Lastly, fighting in World War II, marked as it was by rapid movement, was dramatically different from the trench warfare of the previous conflict. Early in the war, the Axis powers scored a succession of quick victories and did not need to resort to poison gas.
The fate of the SS John Harvey illustrated the difficulty of shipping poison gas. The ship sailed from the United States to Italy in 1943, carrying 2,000 bombs loaded with mustard gas. Each bomb held 60 to 70 pounds of the gas. The ship docked at Bari on 28 November 1943. Four days later, German aircraft attacked the port. Their 20-minute assault sank 17 ships and badly damaged 8 others. Racked by explosions, the John Harvey sank, and some of the mustard gas in the bombs in her hold was released. It mixed with the oil and smoke and rolled across the water. More than 1,000 Allied soldiers and Italian civilians died as a result, and hundreds were blinded, some permanently. The death rate was particularly high because no one knew of the cargo until several weeks had passed.
Yet such difficulties did not preclude the use of poison gas in the war. The Italians, for example, utilized mustard gas and tear gas grenades in their 1935–1936 conquest of Ethiopia. They employed it to protect their flanks by saturating the ground on either side of the advancing columns. They also targeted Ethiopian communications centers and employed mustard gas against Ethiopian military personnel. In fact, the Italians deployed more than 700 tons of gas against the local population, either as bombs (each container contained about 44 pounds) or sprayed from aircraft. Their use of chemical weapons was indiscriminate, targeting both military and civilian areas. One-third of all Ethiopian military casualties in this conflict resulted from exposure to chemical agents.
The Italian decision to employ chemical weapons on a large scale in Ethiopia prompted other nations to renew their production of such weapons and to plan for protecting their armed forces and civilian populations. France began production at a phosgene facility at Clamency in 1936. The U.S. government reopened mustard gas and phosgene plants in New Jersey the following year. The Soviet Union opened three new chemical weapons production plants. And in November 1938, after the Munich Conference, the British government issued tens of thousands of gas masks to civilians and mandated a minimum level of production of 300 tons of mustard gas per week, with 2,000 tons held in reserve.
At the beginning of World War II, Germany held a commanding lead in the stockpiling of chemical weapons, but its government officials did not know this. German stockpiles in 1939 are estimated at 10,000 tons, as compared with 500 tons in Great Britain, 1,000 tons in the United States, and 2,000 tons in Japan.
During World War II in the European Theater, chemical weapons were never deliberately employed on a large scale. In June 1940, British Prime Minister Winston L. S. Churchill discussed with his cabinet the idea of using poison gas to repel a German invasion of either Great Britain or Ireland. Although many of the senior military staff opposed this notion, the cabinet approved it. The British government also considered the use of poison gas to combat the German V-1 and V-2 rockets later in the war. By 1944, Germany's production capacity was 10,000 tons of poison gas per month; in addition, myriad delivery systems were available, including grenades filled with hydrogen cyanide and machine guns capable of firing bullets faced with tabun or sarin. The Luftwaffe had more than 480,000 gas bombs, ranging in size from 33 to 1,650 pounds.
In the Pacific Theater, the Japanese were also involved in massive production of poison gas and had been since the later portion of World War I. By 1937, Japan was daily producing up to 2 tons of lewisite, a virulent form of mustard gas. In their invasion and occupation of China from 1937 to 1945, the Japanese employed a wide variety of poison gases, including phosgene, hydrogen cyanide, mustard gas, and Lewisite. Since the Chinese population, both military and civilian, was completely unprotected against chemical warfare, the effects were devastating.
The Japanese deployed the chemicals weapons by aerial bombardment and artillery shells. They also designed rockets capable of holding 10.5 quarts of a chemical agent and traveling up to 2 miles; flamethrowers that propelled hydrogen cyanide; and a handheld antitank weapon that employed hydrogen cyanide. The Japanese also utilized gas grenades during the Imphal Campaign in 1944. The United States considered using poison gas during the invasion of Iwo Jima and the proposed invasion of the Japanese home islands, but the former was never ordered and the latter proved unnecessary.
The deadliest form of chemical warfare at that time, nerve gas, was never used in battle. A German scientist, Gerhard Schrader, employed by I. G. Farben in 1936, discovered tabun while he was trying to create a more powerful insecticide. Tabun can be absorbed directly into the body and is colorless and odorless. It stops the nervous system from producing a key enzyme, acetylcholinesterase, that allows contracting muscles to relax. If this enzyme is not active, important muscles, such as the heart, contract and begin to spasm. As all the body's muscles contract, the person suffocates. Tabun is 100 to 1,000 times more deadly than chlorine gas and 10 to 100 times more deadly than mustard or phosgene gas. Later, Schrader discovered a second and even more toxic nerve gas, which he named sarin. It is almost 10 times more lethal than tabun. In 1944, a still more deadly nerve gas, soman, was discovered, but it was never mass-produced during the war. Great Britain also manufactured sarin and soman.
Germany's leaders chose not to deploy tabun, since they lacked the ability to protect their own population against this nerve gas and no known antidote existed. The Germans did test their nerve gases on unwilling inmates of concentration and prisoner-of-war camps. At the Natzweiler concentration camp, tests with both mustard and phosgene gases were also conducted on unwilling prisoners. Germany moved its storage of nerve gas in 1944 in anticipation of Allied advances in the west, but their production facility in Silesia fell into Soviet hands.
The German government also used a poison gas, namely, Zyklon B, against prisoners in concentration camps and in its killing centers in Poland. Zyklon B was developed in the 1930s by Deesch, a subsidiary of I. G. Farben that was experimenting with more powerful insecticides. Zyklon B, also known as Prussic acid, is hydrogen cyanide—a powerful, toxic, volatile, and colorless liquid. In order to transport the gas, it was absorbed by wood circles or small cubes because of its great volatility.
Zyklon B was dropped into gas chambers and caused suffocation, as well as feelings of fear and dizziness and vomiting. The Germans constructed gas chambers to use Zyklon B in their camps at Auschwitz, Buchenwald, Sachsenhausen, Neuengamme, Majdanek, Mauthausen, Stutthof, Lüblin, Gross-Rosen, Ravensbrück, and Treblinka. In Auschwitz alone, more than 2.5 million people were murdered through the use of Zyklon B between May 1940 and December 1943. At other concentration camps and killing centers, prisoners were killed by carbon monoxide poisoning.
By 1945, the major combatants as a group had stockpiled more than 500,000 tons of chemical weapons, led by the United States with 110,000 tons. This amount was five times the total amount of gas employed in World War I. Although poison gases were never used in large-scale attacks during World War II, the threat was present throughout the conflict. Given their deadly nature, the updated deployment systems, and the large stockpiles, chemical weapons could have played an enormous role in World War II.
Laura J. Hilton
Clarke, Robin. The Silent Weapons. New York: David McKay, 1968.; Cookson, John, and Judith Nottingham. A Survey of Chemical and Biological Warfare. New York: Monthly Review Press, 1969.; Harris, Robert, and Jeremy Paxman. A Higher Form of Killing. New York: Hill and Wang, 1982.; International Institute for Peace and Conflict Resolution. The Problem of Chemical and Biological Warfare. Vol. 1, The Rise of CB Weapons. Uppsala, Sweden: Almquist and Wiksell, 1971.; Price, Richard M. The Chemical Weapons Taboo. Ithaca, NY: Cornell University Press, 1997.; Spiers, Edward. Chemical Warfare. Urbana: University of Illinois Press, 1986.