Irritating agents (teargas) were the first chemical warfare agents used during World War I.
Used by the French in August 1914, their effects were minimal. However, this initial use led to German experiments with irritating agents. When none were effective on the battlefield, Germany used their experience with development and deployed chlorine gas for the first time on 22 April 1915. They did so hoping to break the tactical stalemate in Flanders Fields, Belgium, that had occurred secondary to trenching, mud, wide open spaces, and reinforcements on both sides. Like nearly all chemical warfare agents used during the conflict, chlorine is heavier than air, making it ideally suited to settling into trenches and bunkers, something neither gunfire or artillery did well.
The use of chlorine gas worked well enough that approximately 5000 Allied soldiers were effected.
Some claim that number may have been inflated secondary to propaganda. Even Germany was surprised by how effective the chlorine gas released from cylinders on the battlefield was. The use temporarily opened a several mile gap in the Allies’ frontlines. Not anticipating it would be so successful, the Germans were not prepared to exploit the temporary but massive tactical advantage the agent generated. Ultimately their advance was stopped at Kitchener’s Wood by Canadian forces. Two days later, the Germans used chlorine gas against Canadian forces again. This time the use allowed the Germans to take hill 60 from the Allies on 5 May 1915. Germany would use chlorine gas several times over the next few weeks.
Chlorine gas is a yellow-to-green vapor with an irritating bleach odor. When it comes in contact with water, it forms hydrochloric acid. This leads to burning of the eyes, nose, mouth, and mucus membranes. Though there is no systemic absorption of the agent, but combined with the moisture and surfactant in your lung alveoli, it causes a direct corrosive effect leading to pulmonary edema. This presentation is sometimes termed “reactive airway dysfunction syndrome” as it manifests with wheezing, tachycardia, and tachypnea.
Chlorine is now one of the most commonly manufactured chemicals worldwide that can also be used as a chemical weapon.
Although effective as a chemical warfare agent, chlorine had its disadvantages. First released as a vapor from cylinders (25,000 cylinders used by the Germans at Reims), it depends on weather and wind patterns for dispersion. This made infantry advances following gas release dangerous for both sides.
The use of chlorine gas did not allow the German attack to reach its entire objective of capturing Ypres, but it demonstrated the effectiveness of chemical warfare agents. Ypres would remain a testing ground for multiple additional chemical warfare agents throughout World War I.
The advent of protective masks
The Allies, seeing the effectiveness of chemical warfare agents, also began researching, developing, and using them. The Allies developed their first protective mask in September 1915. With the Allies and Germany using chemical warfare agents, this led to a competition to develop better protective masks, more potent chemicals, and long-range delivery systems.
Germany moved on to phosgene which was similar to chlorine but more effective.
First used in 1916, phosgene, although still a gas with the same issues as chlorine, was 18 times more potent. Phosgene had a less dramatic smell, making detection more delayed. This, combined with its low water solubility which didn’t cause the mucus membrane/eye burning from chlorine, resulted in longer exposures.
Symptoms typically did not occur immediately but instead within 24 hours, allowing maximum contamination. Protective masks, when worn, would negate the effect of phosgene, but with the delayed onset of symptoms, soldiers could be exposed to a potentially fatal dose without being aware. Phosgene dissolves in pulmonary surfactant, which causes atelectasis, alveolar capillary membrane damage, resultant pulmonary edema, and hemoconcentration when fluid in your blood moves into your lungs. This was sometimes called ”dry land drowning.” Phosgene was responsible for more deaths (85%) than any other chemical agent used during the war.
The USSR was known to have a huge stockpile of Phosgene before their collapse.
The use of Cyanide on the battlefield
Two months after the first use of phosgene by Germany, the French fired hydrogen cyanide deployed in artillery shells. France produced 8 million pounds of hydrogen cyanide during WWI.
As the only chemical warfare agent lighter than air, it dissipated on the battlefield before it could be effective, being present only for a few minutes in open areas. However, it still represents a hazard in confined spaces/buildings.
As a highly water-soluble vapor, cyanide can irritate mucus membranes, eyes, and airways. Some refer to cyanide as a “blood agent” because it damages the oxygen-carrying capacity of red blood cells, but this is now considered an antiquated term, as it more precisely causes asphyxiation at the cellular level.
Interestingly, although often quoted to smell like “bitter almonds,” apparently 20 – 50% of the population can not smell it, as this ability is a genetic trait.
The advancement in protective masks made purely inhalational agents less useful.
In July 1917, Germany began using mustard agents.
They had the advantage of not just being an inhalation agent but also blistered unprotected body sites.
Sulfur Mustard is not truly a gas, but is actually more of an oily liquid that can form a vapor in warmer temperatures. It is felt to have been responsible for the most injuries from chemical warfare agents in World War I. However, because of protective masks, its fatality rate was fairly low (around 2%). As an oily liquid, it could be effectively used as an area denial weapon. However, that made occupying contaminated enemy trenches hazardous.
Typical uniforms/clothing did not offer much protection against sulfur mustard. The agent frequently causes skin damage in sweaty and moist areas, particularly the axillae and perineum. Wearing wool WWI military uniforms provided ample surfaces for this effect.
The shown “reverse sunburn” pattern of skin involvement is classic for mustard agents. The drawing on the left is from the Atlas of Gas poisoning, and the photo on the right is of a mustard-exposed Iranian soldier during the Iran/Iraq war in the 1980s.
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