The Nazi origins of deadly nerve gases

Among chemical weapons, nerve gases are arguably the most nefarious. Trace amounts can wreak long-term havoc on a victim’s nervous system, and high doses can cause painful deaths, typically by asphyxiation.

Nerve agents have been used by armies and terrorists alike. They were dispatched on the battlefield of the Iran-Iraq War, during the Tokyo subway attack of 1995, and more recently on demonstrators in Syria. Despite their infamy, these chemical weapons have a curious history unknown to many people: Eighty years ago, just before World War II began, nerve agents were invented in Nazi Germany. During the Third Reich, German scientists developed bombs capable of deploying the chemical weapons on the Allies, and the Nazi armed forces secretly stockpiled nerve gas munitions.

Had Germany employed nerve agents on the battlefield or for strategic attacks against British cities, “there was little doubt that the initial effects would have been devastating,” noted the late chemical weapons expert Jonathan B. Tucker in “War of Nerves.”

Read on to find out about the accidental discovery of nerve agents, why Adolf Hitler did not drop them on Allied troops, and how their worldwide proliferation was partly the result of the Cold War rivalry between WWII victors.

As it happens so often in science research, nerve agents were discovered accidentally. Gerhard Schrader, a 33-year-old German chemist at the IG Farben chemical conglomerate, had been tasked with developing new insecticides. The goal, mandated by Third Reich strategists, was to reduce Germany’s reliance on food imported from abroad. To do so, the country needed to prevent insect pests from depleting its food supply.

After several setbacks—Schrader had failed to make viable fluorine- and sulfur-based pesticides—the chemist began to experiment with molecules that combined phosphorus and cyanide. An early candidate was so poisonous that exposure to trace amounts sent Schrader to the hospital for several weeks. Then on Dec. 23, 1936, Schrader built a compound he called Preparation 9/91. It was a dramatic poison: Dilute solutions destroyed insect food pests and also caused vomiting, shortness of breath, pupil dilation, drooling, sweating, diarrhea, and death in apes and other mammals.

By the metrics of his employers, Schrader had failed: Pesticides should selectively kill pests, not a wide variety of animals. Given the molecule’s toxicity to humans, however, IG Farben alerted the German military about this poisonous new compound.

At the northwest edge of Berlin lies the imposing 16th-century Spandau Citadel. Most visitors to the spectacular site—which today hosts musical concerts, theater, weddings, seasonal fairs, and a bat sanctuary—aren’t aware that during the Third Reich, the citadel hosted a suite of scientists developing chemical weapons secretly, in direct contravention to the Treaty of Versailles, WWI’s peace accord.

When German army scientists at the Spandau Citadel first analyzed Schrader’s Preparation 9/91, they were so impressed by its toxicity that they named it tabun, after the German word for taboo, Tabu. Existing chemical weapons such as mustard gas and phosgene took hours to days to kill victims, but tabun required only 20 minutes. The army gave Schrader and a colleague a 50,000 mark reward (about $20,000 at the time) for the discovery.

Soon German military researchers began weaponizing tabun, finding ways to insert it into projectiles that could be safely stored without leakage. Other scientists tested the compound on animals, developed processes to manufacture the poison, researched antidotes, and tried building analogs. In 1938, Schrader synthesized a new nerve agent that was twice as toxic as tabun to monkeys. By June 1939, he had brought news of the new compound, called Substance 146, to the Spandau Citadel, where military chemists began developing new methods for producing it and studying its physiological effects. The poison was renamed sarin, an acronym built from the last names of scientists who had spearheaded its development: Schrader, Otto Ambros, Gerhard Ritter, and Hans-Jürgen von der Linde.

As WWII loomed, the German military built a tabun pilot plant capable of producing 400 kg of the poison at a forested site called Raubkammer near the city of Münster. There they tested aerial bombs containing tabun and discovered that the most deadly way to deploy the not-so-volatile agent was to use a small detonation to disperse it as a mist.

By the spring of 1943, a few years into the war, the first large-scale tabun factory near Dyhernfurth, a small town 40 km away from what is now Wrocław, Poland, was producing 350 metric tons (350,000 kg) of tabun per month. By the end of the war, the factory had produced 12,000 metric tons of tabun and loaded it into aerial bombs and artillery shells.

Dyhernfurth was a forced labor factory: Over the course of the war, hundreds of inmates died of toxic exposure, overwork, disease, and malnutrition, and they looked like “walking corpses” to nearby town residents.

Despite all the effort expended on tabun, by the war’s midpoint, it was becoming increasingly clear to military researchers that sarin was a better chemical weapon: Sarin was more volatile and toxic than tabun, even though sarin was more challenging to manufacture. In 1943, the German military approved construction of an entirely new sarin factory at Falkenhagen, a site 70 km outside Berlin.

In 1943, the German Army Ordnance Office recruited Richard Kuhn to study nerve gas. Kuhn was an extraordinary chemist—he won the 1938 Nobel Prize in Chemistry for his efforts to understand the structure and function of vitamin B and carotene compounds. He was also an ardent Nazi, with a penchant for signing off his scientific presentations and correspondence with “Sieg Heil.” Kuhn and his colleagues were tasked with determining the mechanism by which nerve agents caused damage. They discovered that nerve agents block an enzyme called cholinesterase, which is responsible for breaking down acetylcholine, a neurotransmitter that is released into the synapses that connect nerve cells to other nerve cells or muscle cells during electrical signaling. When this enzyme is blocked, nerve cells in the brain and muscles are stuck in an overstimulated state, leading to a wide variety of symptoms including excessive sweating and salivation, pinpoint pupils, vomiting, seizures, and asphyxiation. As part of their research, Kuhn and colleagues synthesized a brand-new nerve agent, soman, which was twice as good as sarin at inhibiting cholinesterase.

From the start of WWII, some in the military were raring to dispatch their nerve weapons “on a very large scale against the enemy hinterland by air strikes,” noted German Colonel Hermann Ochsner in 1939. He said at the time: “There is no doubt that a city like London would be plunged into a state of unbearable turmoil that would bring enormous pressure to bear on the enemy government.” But Hitler demurred, even after Germany’s spectacular defeat at Stalingrad over the winter of 1942–43, which many believe was a turning point in the war. Why did Hitler veto their use?

Some historians point to the fact that Hitler had been a victim of chemical weapons—probably mustard gas—during WWI. As a result of this experience, Hitler believed using poison gas on the battlefield was unethical, an incredibly inconsistent position given his directive to use Zyklon B and other poisonous gases to kill millions of concentration camp prisoners. But it might not have been his personal experience that made Hitler stall on deploying nerve agents. The German Army had had enormous success with its Blitzkrieg strategy: fast and furious attacks using tanks and bombers, followed by foot soldiers. So the use of nerve agents by bombers would have contaminated the very area the army would have then had to occupy. There was also concern that the Allies had discovered the potent chemical weapons and would retaliate.

The Allies had no idea that the German military had discovered and was stockpiling a suite of extraordinarily toxic chemical weapons. But they could, and should, have known. In May 1943, after Germany lost a six-month battle in Tunisia, Allied forces took some 230,000 Axis soldiers prisoner. Among these prisoners of war was a German who informed British interrogators that he was a chemist who had worked at a secret chemical weapons institute—the Spandau Citadel in Berlin—on a new poison with “astounding properties.” His descriptions of the colorless, nearly odorless chemical that could kill victims in just 20 minutes sounded like it might be too good to be true. Although the soldier’s interrogators believed the story, British intelligence officers back in England did not. The 10-page report filed by the interrogators was ignored.

In the last months of the war, Hitler became increasingly apocalyptic, saying to his second-in-command, Albert Speer: “If the war is lost, the nation shall also perish.” In March 1945, Hitler issued a scorched-earth policy, called the Demolitions on Reich Territory Decree, commanding the destruction of German infrastructure to prevent it from falling into the hands of advancing Allies. Fearing for the country’s postwar future, Speer disobeyed parts of the directive.

In a subsequent postwar memoir and elsewhere, Speer made self-serving claims that he considered assassinating the Führer with tabun or one of the chemical weapons used in WWI. Speer said he began searching for a way to deploy the poison into Hitler’s underground Berlin bunker, where the dictator spent a majority of his time. Before the assassination attempt could be enacted, however, Speer claims Hitler ordered increased security around the bunker and blocked the bunker’s air vent with a 3-meter-high chimney because the dictator feared the approaching Russian Red Army might try to poison the bunker’s air.

Many find Speer’s story unconvincing: Skeptics think it absurd that one of the most powerful men in the Reich couldn’t find a ladder high enough to overcome the air vent’s chimney. Furthermore, after WWII, many former Nazis told blatant lies about their past to improve their image, legitimize their actions, and avoid prosecution. For example, Speer long claimed he knew nothing of the Holocaust, but documents discovered after his death reveal he was aware of what was happening at the Auschwitz concentration camp.

In early 1945, as the Allies continued to gain ground on German territory, the German Army went to extremes to hide their tabun- and sarin-filled munitions, “which are presumably not known to the enemy, [and] must under no circumstances fall into his hands,” noted a directive from German Field Marshal Wilhelm Keitel. But transporting these munitions to more secure areas was a challenge, in part because many railroad tracks had been bombed and the country was under frequent Allied air strike. In one catastrophic event, U.S. fighter pilots—unaware of the secret chemical cargo—dropped bombs on freight cars loaded with tabun-filled munitions near Lossa, Germany: Four of the town’s residents died from the fumes in minutes. In the end, thousands of tabun-filled bombs were transported for safekeeping primarily by barge, along rivers such as the Danube and Elbe.

As the Red Army approached the tabun factory at Dyhernfurth, the German military marched thousands of forced laborers off the compounds with little protection from the winter temperatures. Many who survived the exposure were murdered by the German secret police to prevent anyone who had participated in nerve gas production from spreading secrets. Still, the Russians discovered the tabun and sarin production plants, and once they found out about the new nerve agents, they disassembled the factory and reassembled it in Stalingrad.

American soldiers first encountered the secret chemical weapons when they shelled a barge traveling down the Danube River in Bavaria: To the American soldiers’ surprise, after just a few rounds of fire, the Germans waved surrender flags and admitted that the cargo—tabun-filled bombs—could kill them all. Meanwhile, the British Army discovered a bounty of files about the Spandau Citadel’s chemical weapons research hidden at Raubkammer, the initial testing site for tabun. As Allied scientists discovered that some German munitions contained a potent, unknown organophosphorus nerve agent that was much more toxic than anything they had in their own weapons inventory, they began to scramble to get their hands on the military spoils. Soon the Americans and British pooled resources and began searching for and rounding up scientists involved in chemical weapons research: When they arrested tabun inventor Schrader at his home, he immediately handed over chemical formulas and other details of the nerve agents. When American and British intelligence discovered that the Russians had rebuilt Dyhernfurth’s tabun and sarin plants in Soviet territory, there was no doubt a chemical arms race was under way.

As tensions rose between the U.S. and the Soviet Union, both burgeoning superpowers recruited German military scientists to their respective lands to capitalize on the Third Reich’s technological innovations. In the U.S., a paperclip was affixed to the file of any scientist who seemed desirable as a recruit. Then-president Harry Truman didn’t want militant Nazis brought to America, but many of the most promising scientists had been Nazi Party members. As a result, U.S. Army recruiters whitewashed the files to remove Nazi affiliations, wrote new biographies for the scientists, and issued them military security clearance and tickets to America.

The most famous beneficiary of Operation Paperclip was Wernher von Braun, who headed Nazi missile research, was a Nazi Party member, and then went to work for the U.S. National Aeronautics & Space Administration after the war. His expertise is widely cited as one reason U.S. astronauts were the first to reach the moon. Dozens of chemists were also recruited to work on chemical weapons at Edgewood Arsenal in Maryland and on synthetic fuels with the U.S. Bureau of Mines. The British Army had a similar program called Operation Matchbox. Working with other scientists, these former enemy chemists went on to help design, militarize, and stockpile next-generation nerve agents until the Chemical Weapons Convention entered into force five decades later, in 1997. 

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