ONE WILD WORLD — NEWSLETTER

ISSUE #042 · THIS CHANGED EVERYTHING · JULY 2026

There is a version of this story you may already know, and it goes like this. A German chemist named Fritz Haber worked out how to pull nitrogen out of the air and turn it into fertiliser, which is why the planet can feed eight billion people. Full stop. Nobel Prize. Onward to the next fact.

That version is true. It is also missing about seventy per cent of the man.

The full version is that the same Fritz Haber travelled to Belgium in April 1915, stood on a ridge above a French trench, and gave the order to open a bank of steel cylinders containing one hundred and sixty-eight tons of chlorine gas. He watched the yellow-green cloud drift into the enemy line. He is, by any honest reckoning, the founding figure of modern chemical warfare.

Ten days later, back home in Berlin, his wife took his service pistol into the garden and shot herself through the heart.

Three years after that, the Nobel committee gave him the prize.

Nineteen years after that, the country he had served — obsessively, patriotically, to the point of infamy — declared him a Jew and threw him out.

The year after that, he died of a heart attack in a hotel in Basel, on his way to Palestine.

Seven years after that, an institute he had founded delivered a pesticide whose successor was used to murder several of his own cousins in Auschwitz.

None of that is embellishment. All of it is on the record. The problem is not that the story is uncertain. The problem is that it is exactly this, and there is no version of Fritz Haber that lets you feel one clean feeling about him.

To understand why Haber matters at all, you have to understand nitrogen.

Every living thing on the planet needs it. It is in every protein, every strand of DNA, every enzyme. And there is, in one sense, plenty of it — nitrogen makes up seventy-eight per cent of the air you are breathing as you read this. The catch is that atmospheric nitrogen is a stubbornly inert gas. Plants cannot use it directly. They need it in a form — an ammonia or a nitrate — that until the twentieth century could only be produced by a narrow set of bacteria, by lightning strikes, or by mining ancient bird droppings off Pacific islands.

By 1900 the industrialised world was running out of the droppings, and the arithmetic had begun to look ugly. Thomas Malthus’s ghost was rattling the door. In 1898 the British chemist Sir William Crookes gave a public lecture warning that without a synthetic source of nitrogen fertiliser, the wheat-eating nations were on course for mass starvation within a generation.

In 1909, in a laboratory in Karlsruhe, Fritz Haber solved it. He combined nitrogen gas and hydrogen gas under enormous pressure and temperature, over a metal catalyst, and produced ammonia — the raw material of fertiliser — directly from the air. It was scaled up to industrial production by the engineer Carl Bosch and the chemical company BASF, and the process still bears both their names.

It is, on some estimates, the most consequential chemical reaction ever performed by human beings.

Set the caveat aside for a moment and take in the achievement. Fritz Haber, working with hydrogen and nitrogen and an iron catalyst, invented a way to make the raw stuff of life out of thin air. If the story ended there, we would build statues to him. In some places, we still do.

The story does not end there.

When war broke out in August 1914, Haber was forty-five and one of the most decorated scientists in Germany. He was also — and this matters — a fervent patriot. He had converted from Judaism to Lutheranism in his twenties, in an era when a Jewish scientist could not hold a senior chair without doing so. He signed the notorious “Manifesto of the Ninety-Three,” the German intellectuals’ declaration of support for the Kaiser’s war. He wore his Iron Cross with obvious pride. He believed, seriously and to his last breath, that a scientist owed his country everything.

That country was losing.

By late 1914 the Western Front had congealed into the trenches, and the German high command was looking for a way to break the deadlock. Haber, by then head of the Kaiser Wilhelm Institute for Physical Chemistry in Berlin, proposed one. Chlorine gas, heavier than air, released from cylinders into a favourable wind, would sink into enemy trenches and drive the men out.

The Hague Convention of 1899 explicitly banned the use of poison-filled projectiles. Haber’s lawyerly workaround was that his gas came out of a pipe, not a shell.

On the morning of 22 April 1915, on a five-mile stretch of the Ypres salient in Belgium, German troops opened 5,730 cylinders. Around one hundred and sixty-eight tons of chlorine drifted across no-man’s-land as a yellow-green fog. Two French colonial divisions in its path — Algerian and Moroccan soldiers, mostly — broke as fighting units.

Fritz Haber was there. He had come from Berlin to supervise personally. He is described in the German army’s own records as the operational head of the attack. He returned to Berlin days later, promoted to captain, and celebrated at a dinner in his own house.

Within weeks the British were retaliating with their own chlorine, within a year the French had added phosgene, and by 1917 the Germans had introduced mustard gas — a weapon so cruel that it killed slowly, over days, from the inside out. By the end of the war, chemical weapons had killed around ninety thousand men and injured more than a million.

Haber oversaw much of the German programme. Colleagues described him as tireless. He personally trained the gas units. He is genuinely, unambiguously, the founding figure of modern chemical warfare. It is not a slur invented by his enemies. It is what he was proud of.

Clara Immerwahr had been the first woman in Germany to earn a doctorate in chemistry. She had been Haber’s brilliant student, then his wife. By 1915 she had, by every account, been miserable for a long time. Their marriage was cold. Her husband was rarely home. Her own scientific career had been quietly dismantled by domestic life. She was, close friends said, deeply depressed.

In the early hours of 2 May 1915, ten days after Ypres and on the night after a dinner celebrating his promotion, she took Haber’s service pistol into the garden of their home in Dahlem, on the outskirts of Berlin, and fired one shot into her heart. Their thirteen-year-old son Hermann found her body.

Haber left for the Eastern Front that same morning, to supervise the first chlorine attack on Russian troops.

The story is not less troubling for being ambiguous. It is more.

In November 1919, the Swedish Nobel Committee awarded Fritz Haber the Nobel Prize in Chemistry — for 1918, delayed by the war — for the synthesis of ammonia from its elements. Not for chemical warfare. For fertiliser.

The reaction from the recently victorious Allies was fury. Haber had been on the initial Allied list of war criminals to be tried under the Treaty of Versailles for the poison-gas programme. He was quietly removed from a later revision of the list, but the political point had been made. Several French and British Nobel laureates boycotted the ceremony. At Cambridge a few years later, Ernest Rutherford would refuse to shake Haber’s hand.

The committee’s defence, then and afterwards, was that the prize was awarded specifically for the ammonia work, which had transformed agriculture, and that the wartime activities of the recipient were not the business of a scientific award. That is a coherent position. It is also the position under which one could give the prize to almost anyone.

Haber accepted the medal in June 1920, in Stockholm. He gave a lecture on nitrogen. He did not mention chlorine.

This is the part of the story where the internet gets it wrong, and the truth is bad enough without the exaggeration.

You will read, in a lot of places, that Fritz Haber “invented Zyklon B, the gas the Nazis used to murder millions of Jews, including members of his own family.” That is not correct in the specific sense. The correct version is worse in a subtler way.

In the early 1920s Haber’s Kaiser Wilhelm Institute chaired a Technical Committee for Pest Control. Under his patronage, a group of chemists developed a hydrogen-cyanide pesticide called Zyklon — later renamed Zyklon A — for fumigating grain silos, ship holds and delousing depots. It was marketed by a company called Degesch, spun out with Haber’s involvement. When Degesch was sold on to the chemical firm Degussa in 1922, its chemists — no longer under Haber — reformulated the compound into a more stable pellet with a warning odorant added. That reformulation became known as Zyklon B. The odorant was later stripped out at SS request. That is the gas that was used in the chambers at Auschwitz, Majdanek and Mauthausen from 1941 onwards.

Haber himself died in 1934. He did not invent Zyklon B. He founded the institute and the pesticide programme it grew out of. The chemists who made the killing formulation were his intellectual heirs, not himself, and it is impossible to know whether he would have been horrified, or would have found some patriotic accommodation, if he had lived to see it.

What is not open to argument is that several of his cousins, and members of the broader Haber family, were murdered in Nazi camps, some of them with a poison whose lineage began in his laboratory.

In April 1933, the Nazi government passed the Law for the Restoration of the Professional Civil Service, which mandated the dismissal of Jewish scientists from state institutions. Haber, by then sixty-four and world-famous, was technically exempted as a war veteran. He was ordered instead to sack every Jewish member of his staff.

He refused.

His resignation letter, dated 30 April 1933, is a document that ought to be read into the story more often than it is. He told the ministry that a scientist’s tradition of choosing collaborators purely on their qualifications was more than four hundred years old, and that he was too old to learn a new one. He walked out.

He tried to find a position elsewhere. Cambridge took him in for a few uncomfortable months — Rutherford, still refusing the handshake. Chaim Weizmann, the Zionist leader and himself a chemist, arranged a senior post for him at what would become the Weizmann Institute in Palestine. In January 1934, ill and exhausted, Haber set off. He got as far as Basel, where he collapsed in a hotel room and died of a heart attack on 29 January. He was sixty-five.

His ashes were later interred beside those of Clara in Basel’s Hörnli cemetery. He had outlived her by nineteen years.

Follow the two threads forward and they land on your kitchen table.

The bread you had for breakfast almost certainly contains nitrogen that passed through a Haber–Bosch reactor. Roughly half of the protein in your body was assembled, ultimately, from ammonia synthesised out of thin air by the process he invented. Without it the planet could not feed itself, and everyone alive knows that or is about to.

The second thread runs from the ridge at Ypres through the mustard gas of 1917, the tabun and sarin work of the 1930s, the sarin attacks in Tokyo and Damascus and Idlib, and every chemical-weapons convention the world has since tried and failed to enforce. The genie he let out has never gone back into the bottle.

He is a genuine paradox — not a rhetorical one. Not a “well, everyone has flaws” paradox. He is the person who arguably kept more human beings alive than any single individual in history, and the person who invented the systematic use of poison as a weapon. He is not, on balance, one thing or the other. He is both maximum things at once.

This is not a story with a clean moral. Or rather, the moral is that human beings and their inventions do not resolve into neat columns of good and evil. Sometimes the same brain, in the same lifetime, does both — and the world takes the fertiliser gratefully and lets the gas drift on into the next century.

Half the nitrogen in your body was put there by Fritz Haber.

So was the entire modern idea of a poison-gas attack.

Vaclav Smil — Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production (MIT Press, 2001). The definitive source for the “roughly half of humanity” estimate and the historical arithmetic of nitrogen fertiliser.

Daniel Charles — Master Mind: The Rise and Fall of Fritz Haber, the Nobel Laureate Who Launched the Age of Chemical Warfare (HarperCollins, 2005). The best English-language biography; source for Haber’s presence at Ypres, the sequence of events around Clara’s death, and the exile years.

Bretislav Friedrich and Dieter Hoffmann — “Clara Haber, née Immerwahr (1870–1915): Life, Work and Legacy” (Zeitschrift für anorganische und allgemeine Chemie, 2016). The scholarly correction of the popular “Clara died in protest” narrative, tracing its origin to the 1990s.

Wollheim Memorial (Fritz Bauer Institut, Frankfurt) — “Zyklon B: An Insecticide Becomes a Means for Mass Murder.” Source for the pesticide-to-gas-chamber chain, and the corrective on what Haber himself did and did not do.

United States Holocaust Memorial Museum — Encyclopedia articles on the persecution of Jewish scientists and the Zyklon B supply chain; context for Haber’s 1933 resignation and the fate of the wider Haber family.

Nobel Prize Foundation — 1918 Chemistry laureate citation and surrounding correspondence at nobelprize.org, including the Allied boycott.

Britannica and Encyclopedia.com biographical entries on Fritz Haber and Clara Immerwahr — cross-checked with the above for dates, ranks, and the Rutherford incident at Cambridge.

Note on Zyklon B: Haber’s Kaiser Wilhelm Institute developed the original hydrogen-cyanide pesticide programme in the early 1920s. The specific formulation known as Zyklon B was reformulated by Degesch chemists after Degussa purchased the company in 1922, and was first used for mass murder in 1941 — seven years after Haber’s death. The lineage is real; the popular “he invented the gas that killed his own family” is a compression that shortens the chain.

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