Chemical Warfare

Encyclopædia Britannica Article
Britannica

The use of chemical compounds, usually toxic agents, in warfare, and also the methods of combating such agents. Though smoke, which is used for camouflage or to confuse an enemy, and incendiary weapons are covered by this definition, the term usually refers to the use of chemical agents, both lethal and nonlethal, that attack the human organism by paralyzing the nervous system (nerve gases); inducing temporary blindness, deafness, paralysis, nausea, or vomiting; causing severe burns to skin, eyes, or lungs; or stifling respiration. Also included are chemical defoliants and herbicides for military purposes, such as those used in the Vietnam War.

Worldwide revulsion toward chemical weapons is embodied in the Geneva Protocol of 1925, prohibiting “the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices.” More than 140 states, including all major nations, are parties to the Protocol of 1925.

History Of Use:

Toxic smokes and other toxic substances were used occasionally in war from ancient times, but the earliest large-scale use of chemical warfare agents was in World War I. Preceded by both sides' sporadic use of various tear gases in artillery and other projectiles starting in 1914, it was the German attack with chlorine released from thousands of cylinders along a four-mile (six-kilometre) front at Ypres on April 22, 1915, that initiated the massive use of chemicals in that conflict. The wind-borne cloud totally broke the lines of the unprepared French Territorial and Algerian units in its path, but the attackers failed to exploit the opportunity. Although numerous chlorine gas-cloud attacks were subsequently carried out by both sides, they accomplished little, owing to the introduction of gas masks and other protective measures.

As other gases and more effective delivery methods were introduced, so too were improved defenses. Notable among offensive improvements were respiratory agents more poisonous than chlorine, such as phosgene, and chemicals that blistered the skin and attacked the eyes, especially mustard gas. The defense kept pace, with the introduction of better gas masks, protective clothing, and battlefield tactics for minimizing exposure. More than 100,000 tons of various chemical warfare agents were used in World War I; but gas was an unimportant weapon in overall military terms, largely because of the effectiveness of defenses against it.

In World War II, chemical weapons were stockpiled by both sides, but they were not used and were not integrated into military planning. Records indicated various reasons for this: (1) military opinion that chemical weapons would be no more effective than conventional weapons and would complicate and delay operations, (2) fear of retaliation, especially against civilian centres, and (3) aversion to gas warfare by political and military leaders, reflecting the proscriptions of the Geneva Protocol.

Chemical weapons were used in only a few of the more than 200 wars fought after World War I. In each case—as in Ethiopia (1935–36), China (1938–42), the Yemen (1966–67), and Iraq–Iran (1984–88)—chemicals were used against forces initially lacking gas masks.

The Weapons:

Modern lethal chemical weapons employed the organophosphorus nerve agents first produced but not used by Germany during World War II. Related to certain insecticides but much more toxic to man, they would cause intense sweating, filling of the bronchial passages with mucus, dimming of vision, uncontrollable vomiting and defecation, convulsions, and finally paralysis and respiratory failure. Death would result from asphyxia, generally within a few minutes after respiratory exposure or within hours if exposure was through a liquid nerve agent on the skin.

The U.S. stockpile of chemical warfare agents, loaded into munitions or stored in bulk, included the nerve agents sarin and VX, while the Soviet Union stocked the nerve agents sarin, VX, and soman. Of these three nerve agents (all liquids), sarin would evaporate the most rapidly and would pose mainly a respiratory hazard. VX, the least volatile, would act primarily as a contact poison. Soman, with volatility intermediate between that of sarin and VX, would pose both respiratory and contact hazards.

In addition to nerve agents, both nations stocked mustard gas and the irritant CS, which was also used by police. The Soviets also stocked lewisite, a blister agent developed but not used by the United States during World War I. Mustard gas and lewisite would not be nearly so lethal as the nerve agents, causing casualties principally from incapacitating blisters and temporary blindness. Their full effects would take several hours to develop, although lewisite, in contrast to mustard gas, would cause immediate pain to the skin and eyes.

Liquid chemical warfare agents, such as mustard gas, lewisite, and the nerve agents, could be loaded into artillery projectiles, bombs, or missile warheads, to be dispersed by an explosive charge as a vapour cloud or a liquid spray. Liquid agents might also be carried in tanks and sprayed from aircraft at low altitude. Greater persistence and more controlled dispersion might be obtained by the addition of thickeners. Solid agents, such as CS, might be dispersed explosively or aerosolized from pyrotechnic mixtures in various munitions.

An innovation put into quantity production by the United States in 1987 was the binary sarin artillery projectile, in which two relatively nontoxic precursors of sarin were held in separate canisters. Upon firing, the two chemicals would mix and react to form sarin. One of the canisters might be stored and shipped separately, to be inserted into the projectile at the ammunition depot or the gun site. This built-in safety feature was intended to provide greater operational flexibility in the storage and transport of the weapon. The binary principle could be applied to other types of chemical warfare agent.

The amount of a chemical warfare agent required to create a hazardous cloud over a target area would be highly dependent on air movements. The weight of sarin, for example, required to produce a lethal respiratory hazard to unprotected persons over most of an open mile-square area could be between 0.3 and 10 tons, depending on atmospheric conditions. As an illustration, the delivery of these amounts by 155-millimetre artillery would require the firing of approximately 100 to 3,000 projectiles.

For causing casualties to unprotected troops, chemicals could be more effective than an equivalent weight of conventional high-explosive fragmentation weapons. For troops with good protection, however, the reverse would be true; soldiers with modern antichemical protection would be far less vulnerable to chemicals than to conventional weapons.

Defense:

The first and most important line of defense against chemical warfare agents (also needed for protection against radioactive fallout) was the individual protection provided by masks and protective clothing, and the collective protection of combat vehicles and mobile or fixed shelters. Filters for masks and shelters contained specially treated activated charcoal to remove vapours, and paper membranes or other materials to remove particles. Such filters typically could reduce the concentration of chemical (and biological) warfare agents by a factor of at least 100,000. Masks could be donned in less than 10 seconds and could be worn for long periods, even in sleep. Modern protective overgarments were made of fabric containing activated charcoal or other adsorptive forms of carbon. A complete suit typically weighed about four pounds (two kilograms). The fabric could breathe and pass water-vapour perspiration. In warm weather, periods of heavy exertion in full protective gear would have to be limited in order to avoid heat stress, or else protection would have to be partly relaxed, as by partially opening the protective jacket. Under common European conditions, military units routinely exercised at or near full protection for several days continuously.

Other items for chemical defense were detectors and alarms sensitive to nerve and blister agents, prophylactic and antidote drugs that would provide partial protection against nerve agents, and equipment for decontaminating people and equipment.

The effectiveness of chemical weapons against prepared forces would depend more on the interference with fighting performance imposed by wearing protective equipment and taking other precautions than on direct casualties. The extent of such interference, and hence the military value of chemicals in comparison with other weapons, was difficult to assess. Estimates, based on controlled field exercises, of the reduction in performance in military units under chemical attack ranged from near zero to more than 30 percent, depending on the mission and the conditions of the exercise.

Biological Warfare:

Biological warfare agents are infectious microbes, including viruses, bacteria, and fungi, intended for use in warfare because of their pathogenic effects on people, animals, or plants. The development, production, and stockpiling of weapons based on them were outlawed by the 1972 Biological Weapons Convention, to which more than 100 states were party, including all five permanent members of the United Nations Security Council. The treaty also covered weapons based on naturally occurring poisons, known as toxins, however produced. As with chemical weapons, actual employment of biological weapons was outlawed by the 1925 Geneva Protocol.

At the time of their destruction in accordance with presidential directives of 1969 and 1970, the biological weapons of the United States (the only country for which authenticated information was available) included dry-powder or liquid-slurry formulations of the microbes that cause tularemia, Q fever, Venezuelan equine encephalitis, rice blast, and stem rust of wheat. They also included a number of toxins, such as paralytic shellfish poison. A variety of dispensers, both large and small, was also on hand.

Biological weapons designed to dispense airborne clouds of pathogenic microbes could in theory kill or incapacitate unprotected populations over very large areas. Such weapons were never used.

Chemical Weapons. (From the Defining Weapons of Mass Destruction Article)

chemical and biological warfare

chemical and biological terrorism

Biological Warfare (From the Microbiology Article)

Biological warfare (From the Chemical Warfare Article)

The War During 1915 (From the World War I Article)

History of use (From the Chemical Warfare Article)

Criticisms of the genocide convention (From the Genocide Article)

The weapons (From the Chemical Warfare Article)

The Middle East (From the International Relations Article)

Poisons of biological origin (From the Poison Article)

weapon of mass destruction