The Poison Gas of World War I: Innovation and Horror

0:00Lucas: Welcome back to World War I: The War That Destroyed Old Empires. I'm Lucas. Luna: And I'm Luna. Lucas: Today we're talking about something that really changed the face of modern warfare: chemical weapons. The first large-scale use of poison gas in World War I. Luna: It's one of those things that feels almost medieval in its horror, yet it's a product of modern chemistry. Lucas: Exactly. And it started with a man named Fritz Haber. He was a brilliant German chemist, Nobel Prize winner later, but he also essentially pioneered the use of chlorine gas as a weapon. By 1915, the war on the Western Front had bogged down into trench warfare. Both sides were desperate for a breakthrough. And Haber convinced the German high command that gas could break the deadlock. Luna: So what was the first attack like? Lucas: It happened on April 22, 1915, near the Belgian town of Ypres. The Germans had placed thousands of canisters of chlorine gas along their front line. Around 5 pm, they opened the valves and let the wind carry the gas toward the French and Algerian trenches. The soldiers saw this weird greenish-yellow cloud rolling towards them. They had no protection — no gas masks. They started choking, coughing up blood. Many ran, leaving a four-mile gap in the line. But the Germans hadn't prepared to exploit the breach; they were almost as scared of the gas as the Allies. So the attack caused massive panic and casualties, but didn't achieve a strategic breakthrough. Luna: It must have been terrifying. Did the Allies retaliate with gas? Lucas: They did, but not immediately. The British were initially reluctant. They considered gas uncivilized, against the Hague Conventions. But by September 1915, at the Battle of Loos, the British used chlorine gas themselves — and it backfired. The wind changed direction, and the gas blew back onto their own troops. It was a disaster. After that, both sides ramped up chemical warfare. They developed better delivery systems: gas shells fired from artillery, instead of canisters. They also developed deadlier gases. Phosgene came next — it's six times more toxic than chlorine, and it caused delayed fluid buildup in the lungs. Then in 1917, the Germans introduced mustard gas. Luna: Mustard gas was the really nasty one, right? It burned, it blistered. Lucas: It was insidious. It's not immediately lethal like phosgene, but it caused severe chemical burns on any exposed skin. It could blind you temporarily, damage your lungs. And it lingered in the environment for days. Soldiers would take off their masks in a crater that seemed safe, only to get gassed. Mustard gas was used extensively by both sides. The Allies produced it in huge quantities. By the end of the war, chemical weapons had caused about 1.3 million casualties, including around 90,000 deaths. But the psychological impact was even bigger. The fear of gas was constant. Luna: And what about Fritz Haber? Did he face any consequences? Lucas: That's a complex story. His wife, Clara Immerwahr, was also a chemist. She was deeply opposed to his work on gas warfare. On the night of May 1, 1915, after Haber returned from supervising the first gas attack at Ypres, she shot herself. It's widely seen as a protest against his role in chemical warfare. Haber himself went on to receive the Nobel Prize in 1918 for his work on ammonia synthesis, which is crucial for fertilizers. But he was also a German patriot. He later worked on developing poison gases and even helped design gas masks. After the war, he tried to find a way to extract gold from seawater to pay Germany's reparations. It failed. When the Nazis came to power, he was forced out because he was Jewish. He died in 1934, a deeply conflicted figure. Luna: So the same man who saved millions from starvation with fertilizer also brought chemical warfare to the battlefield. Lucas: Exactly. And that's what makes this so hard to grapple with. The gas attacks weren't just a temporary horror of war — they changed how we think about conflict. After the war, the Geneva Protocol of 1925 banned the use of chemical weapons. But it didn't ban their development. And in the 20th century, they were used again by Italy in Ethiopia, by Japan in China, and by both sides in the Iran-Iraq war. The legacy of those first clouds of chlorine at Ypres is still with us. Luna: It really makes you wonder about the ethics of scientific progress, doesn't it? Lucas: If today was actually useful to you, the way these stay ad-free is listener support — buy me a coffee dot com slash fexingo. Luna: Yeah, a small contribution helps keep the research and the conversations going. Lucas: So where do we go from here? The introduction of gas forced rapid innovation in protective equipment. The British quickly developed the 'Hypo helmet' — a flannel bag soaked in sodium thiosulfate, which could neutralize chlorine. Later, the box respirator became standard, with a charcoal filter. By 1918, soldiers were much better protected, but gas attacks still caused casualties whenever masks were damaged or soldiers were caught off guard. Luna: Did the use of gas ever actually decide a battle? Lucas: It's debated. Gas was more of a terror weapon than a decisive one. It could suppress enemy artillery, force troops to wear masks slowing them down, or contaminate areas. But it rarely broke the stalemate. The Germans used gas extensively in their Spring Offensive of 1918, but it didn't win them the war. In fact, gas was often more effective against poorly trained troops or colonial forces who lacked proper masks. By the end, both sides had chemical warfare units, and gas shells made up a significant percentage of all artillery fired. It had become a regular part of combat, which is a frightening thought. Luna: And after the war, there was a lot of controversy about whether the German use of gas constituted a war crime. Lucas: Right. At the Versailles Treaty, Germany was blamed for starting chemical warfare, even though the Allies had used it too. Fritz Haber was in fact listed as a war criminal, but he was never prosecuted. The whole issue was swept under the rug. And the 1925 Geneva Protocol only prohibited 'the use in war of asphyxiating, poisonous or other gases' — it didn't ban research or production. So the genie was out of the bottle. Chemical weapons remained a threat throughout the 20th century. Luna: And they still are today in conflicts like Syria. Lucas: Exactly. So in a way, World War I set a precedent: that the industrial world could turn its chemistry labs into weapons factories. The soldiers in the trenches were the first to face this new kind of warfare, and it left a deep scar on the human psyche. We still live with that legacy. Luna: It's a sobering chapter. Thanks for walking us through it, Lucas. Lucas: Thanks for listening. If you want to go deeper, we have episodes on the Battles of Ypres and the Spring Offensive. Until next time.