A Higher form of Killing

THREE Hitler’s Secret Weapon

TOWARDS THE END of 1936, Dr Gerhard Schrader, a German scientist researching into possible new insecticides, make a remarkable discovery. He had been methodically working his way through an enormous range of organic phosphorus compounds when he suddenly stumbled upon a series of poisons of extraordinary power. On 23 December he managed to prepare some of the chemical for the first time, and tested it by spraying a concentration of just one part in 200,000 on some leaf lice. All of the insects were killed. A few weeks later, in January 1937, Schrader began the first manufacturing trials. Immediately he discovered that what he had at first considered a promising insecticide had side-effects upon man which were ‘extremely unpleasant’.

‘The first symptom noticed,’ he later recalled, ‘was an inexplicable action causing the power of sight to be much weakened in artificial light. In the darkness of early January it was hardly possible to read by electric light, or after working hours to reach my home by car.’¹ The slightest drop of the substance spilt on the laboratory bench caused the pupils of his eyes to contract to pin-points, and he suffered acute difficulty in breathing. After a few days of this, Schrader and his assistant were forced to stop work for three weeks in order to recover. They were lucky to escape with their lives. Inadvertently they had discovered, and become the first victims of, the world’s most powerful chemical weapon, the original ‘nerve gas’: tabun.

It was obvious that there could be no question of using Schrader’s discovery as an insecticide: in tests that spring almost all the animals exposed to even tiny quantities of it were dead within twenty minutes. Instead, under a Nazi decree of 1935 requiring German industry to keep secret any invention with military potential, Schrader was summoned to Berlin to demonstrate tabun to the Wehrmacht.

Its value as a war gas was quickly recognized. Dogs or monkeys poisoned by tabun seemed to lose all muscular control – their pupils shrank to dots, they frothed at the mouth and vomited, they had diarrhoea, their limbs began to twitch and jerk; finally, within ten or fifteen minutes, they went into convulsions and died. In addition to its potency, tabun had other advantages. It was colourless and practically odourless, and it could poison the body not merely by inhalation, but also by penetrating through the skin. The so-called nerve gases were as great an advance over the chemical weapons of the First World War as the machine gun was over the musket.

It was not until the early 1940s that the Nazi scientists began to understand exactly why tabun was such a lethal agent. Unlike the gases of the First World War, which have general effect, the nerve gases inhibit the action of a specific chemical in the body called cholinesterase. Cholinesterase’s function is to control the muscles by breaking down the chemical which causes muscular contraction, acetylcholine. If this is not done, the level of acetylcholine in the body builds up to a disastrous level, sending all the muscles of the body into contraction. The body thus poisons itself, as it loses control of all its functions. The muscles of the arms and legs along with those which control respiration and defecation go into a state of violent vibration. Death comes as a result of asphyxiation.

The Wehrmacht was impressed. Colonel Rüdriger, head of the Army’s poison gas installations at Spandau, ordered the construction of new laboratories to produce sufficient quantities of tabun to begin field trials. Schrader, who worked for the IG Farben chemical conglomerate, was moved to a new factory at Elberfeld in the Ruhr ‘to pursue the study of organic phosphorus compounds undisturbed’.²

A year later, in 1938, he discovered a compound related to tabun – isopropyl methylphosphonofluoridate – whose potential ‘as a toxic war substance’ he found to be ‘astonishingly high’. The new agent was named sarin, a title invented by Schrader as an acronym of the names of the four key individuals involved in its production: Schrader, Ambros, Rüdriger and van der Linde. In June 1939 the formula for sarin was passed on to the Wehrmacht’s laboratories in Berlin. Tests on animals showed it to be almost ten times as poisonous as tabun.

In September 1939, as scientists in Berlin prepared the first samples of sarin, the German army launched its invasion of Poland. For the second time in a generation, German chemists were at the heart of their country’s war effort. On 19 September, after almost three weeks of uninterrupted victory, Adolf Hitler rose to address a tumultuous audience in Danzig. He told them – in a speech clearly designed for Allied ears – of fearsome new German weapons, against which his enemies would be defenceless. It is conceivable that he had in mind the new nerve gases. At any event, that same month the German chemical industry was ordered to put in hand plans to build a new factory capable of producing a thousand tons of tabun a month.

Construction work began in January 1940 in the forests of Silesia in western Poland. The factory was built close to the Oder River, forty kilometres from Breslau, at a place called Dyhernfurth. Its Wehrmacht code-name was ‘Hochwerk’. By 1943 it had cost 120 million reichsmarks. The money came in the main from the Wehrmacht and was funnelled through specially-created companies with only a nominal connection to IG Farben (one of ‘the many ruses attempted and plans entered into for the purpose of enabling the company to disclaim in the post-war period any responsibility whatsoever in providing these outlawed instruments of war’³). The companies included Anorgana, Luranil. Monturon and Montana. Anorgana was the largest, and its managing director, Otto Ambros, one of the most powerful industrialists in Germany, with direct access to Hitler. Six years later at Nuremburg he was sentenced to eight years in prison for ‘slavery and mass murder’. Through Anorgana, Ambros provided the chemists and technicians needed to build and run the Nazi war gas plants.

Dyhernfurth was one of the Third Reich’s largest and most secret factories. It covered an area over a mile and a half long and half a mile wide. Had they won the war, the Nazis planned to turn it into Europe’s largest chlorine factory. It had a monthly capacity for producing 3,000 tons of nerve gas – 500 tons from each of its six separate units. The factory was completely self-contained. It made the intermediate products needed in the manufacture of tabun; it made the tabun itself; and it had a cavernous underground shell-filling plant, where the liquid nerve gas was loaded into aircraft bombs and shells. This last area was one of the most closely-guarded parts of the site. It was artificially ventilated and ‘in the charge of one Dr Kraz’. Under his supervision, ‘the shells were sent out from Dyhernfurth in trucks and by train. The cargoes were always secreted under coverings so that specific markings were not easily detected’.⁴ The charged munitions were stored in a subterranean arsenal at Krappitz in Upper Silesia. Altogether, the factory employed a workforce of 3,000 – all German – who were housed in a vast barracks built in a clearing in the forest.

From the outset the Nazi nerve gas project was beset by difficulties, and it took over two years, until April 1942, to get the factory operational. Many of the chemicals needed to make the liquid nerve gases were found to be exceptionally corrosive and all iron and steel equipment had to be plated with silver. The nerve gas itself was so highly toxic that the whole of the plant ‘was enclosed in double glass-lined chambers with pressurized air circulating between’,⁵ and all apparatus had to be decontaminated with steam and ammonia. The workers wore respirators and special protective suits made of cloth sandwiched between two layers of rubber which were discarded after every tenth wearing. If anyone was suspected of having been contaminated, their clothes were torn off and they were immersed in large baths of sodium bicarbonate solution.

Being drafted to work at Dyhernfurth was a grim prospect. The experience of Dr Wilhelm Kleinhans, a young IG Farben scientist, was fairly typical. In August 1941 he was one of a team of chemists and engineers assembled by Ambros in Ludwigshafen. They were, he informed them, to work for the Reich, in return for which they would be exempted from military service. Before leaving for Dyhernfurth in September, Kleinhans was let into the secret of tabun and sarin by Schrader himself, who told him that the gas mask was not much protection against agents which could penetrate through the skin. Life at Dyhernfurth itself, far from home and in the oppressive forests of Silesia, was both unpleasant and dangerous:

It was discovered that resistance to low concentration of tabun ‘was increased by a higher than average amount of fats’ and all the workers at Dyhernfurth were given extra rations of milk and fatty foods.

Even before production got underway at the factory there were over 300 accident cases. In the two and a half years that it was operational at least ten men were killed. Kleinhans recalled four pipe fitters who died when a large quantity of tabun drained onto them from pipes they were trying to clean. ‘These workmen died in convulsions before the rubber suits could be torn off.’ Schrader knew of a man who had half a gallon of tabun poured down his neck; death occurred in two minutes. In one of the most serious accidents, seven workmen were hit in the face by a stream of liquid tabun which forced itself between the face and the respirator. ‘They became giddy, vomited, and so then removed their respirators thus inhaling more of the gas. On examination they were all unconscious (one or more were still excited but not conscious), had a feeble pulse, marked nasal discharge, contracted pupils and asthmatic type of breathing. Involuntary urination and diarrhoea occurred.’¹⁷ Despite intra-muscular injection of atropine and heart drugs, artificial respiration, cardiac massage and the use of oxygen masks, only two of the seven survived: the moment they both recovered consciousness they had a second bout of convulsions and had to be sedated for ten hours. The bodies of the dead men were autopsied and their organs sent back to Berlin, where their brains and lungs were found to be thickly congested.

If the Germans had any doubts at all about the potency of their nerve gases, the Dyhernfurth accidents must have completely dispelled them. If this was the effect of tabun in a factory, with every modern medical facility to hand, what might its effects prove to be on the battlefield, against unprotected and unsuspecting Allied soldiers? By the middle of 1943, as the rush of German victories began to turn into an ebb of defeats, Hitler started seriously to consider employing his Siegwaffe: his Victory weapon.

By the middle of the war, the Nazis had acquired a vast, hidden armoury of chemical weapons. Despite all the other burdens involved in fighting the war, the Wehrmacht still found hundreds of millions of marks to pump into the production and testing of poison gas. According to a team of experts from Porton Down who investigated the German chemical warfare programme after the war:

The Germans had a score of factories capable of producing around 12,000 tons of poison gas every month. The British and Americans believed around 70,000 ton to have been stockpiled; the Soviet estimate was 250,000 tons. In addition to tabun, the Germans had two types of mustard gas (Somer-Lost and Winter-Lost) for warm and cold climates, and a terrifying incendiary gas, N-Stoff (or chlorine trifluoride) produced exclusively by the SS, which could cause clothes, hair and even asphalt to burst into flames. There was also small-scale production of sarin – the second nerve agent discovered by Schrader – in a closely-guarded compound at Dyhernfurth known simply as ‘Building 144’; by the end of the war a whole factory devoted to the manufacture of sarin, with a capacity of 500 tons a month, was nearing completion at Falkenhagen, south-east of Berlin.

Research and testing was carried out at laboratories at Spandau and at the Truppenhubuengsplatz or training area at Raubkammer, fifty square miles of forest and heath just north of Munster. Between them, the two installations employed around 1,200 people.

The Germans developed a series of ingenious weapons and devices which give some idea of the way Hitler might have been able to use his chemical arsenal. To slow up an enemy advance, for example, Raubkammer produced various methods of ground contamination. One was

A separate team of scientists at Raubkammer known as ‘Group X’ worked specifically on anti-personnel weapons.

A machine gun was tested capable of firing 2,000 rounds of ammunition a minute charged with tabun or sarin ‘with the object of attacking tanks by creating a concentration of gas round the air inlets’. Another anti-tank weapon was the gas grenade. Tests on captured tanks produced good results: ‘it was thought that even if death did not take place, the crew would be rendered unconscious for sufficient time to enable the tank to be captured intact or destroyed.’¹¹

The Luftwaffe had almost half a million gas bombs, ranging from 15 kg anti-personnel devices up to 750 kg phosgene bombs. Copying the design of captured Russian spray tanks, German pilots learnt to spray columns of marching men so effectively that 50 per cent of the troops were contaminated, even if they managed to get into their gas masks and capes in time – ‘this was found even with troops who had been attacked and knew they were likely to be attacked again.’¹² Hydrogen cyanide, mustard and tabun were the best agents. The Germans also tried spraying concentrated acids and alkalis: ‘fuming nitric acid was thought to be of some value in a low spray owing to the painful burns produced’.¹³

The Nazis carried out a successful series of tests, charging their flying bombs and rockets with poison gas. In 1939, Hermann Ochsner, the General in command of all German chemical troops, advocated the use of gas ‘against industrial concentrations and large cities’ as a weapon of terror. ‘There is no doubt that a city like London would be plunged into a state of unbearable turmoil which would bring enormous pressure to bear on the enemy Government.’¹⁴ Now, in the V-weapons, the scientists had the means to deliver the terror which Ochsner – and Hitler – desired. According to the Porton scientists, ‘plans were in hand to fill the V-i with phosgene in place of the normal 800 kg of hexa-TNT’.¹⁵ The Raubkammer experts had also made plans to use the V-weapons to deliver nerve agents into the very heart of London; the British standard civilian respirator would have offered little protection against tabun. Considering the fact that on some days during 1944 the Nazis were able to send flying bombs over the English coast in waves of 200 at a time, Hitler had here a terror weapon of horrifying dimensions.

Like the British and Americans, the Germans made extensive use of animals and human ‘observers’ in their testing of poison gases. Men crawled over contaminated ground on their hands and knees; others, wearing bathing costumes and oxygen cylinders, sat in gas chambers filled with hydrogen cyanide. ‘Chemicals were fired into woods and human subjects entered the area to see how long they could remain there without adjusting their respirators.’ For testing mustard gas rabbits’ ears were used, as was shorn horse skin; ‘the skin between a dog’s toes’ was found to be particularly good ‘for comparison with humans’.¹⁶

The Allied investigators’ most grisly find at Raubkammer was a Black Museum whose exhibits included the organs of animals gassed with tabun, and ‘some 4,000 photographs mounted in albums and folders’. The photographs were of men wounded or killed by gas in accidents or experiments. ‘Due to the gruesome appearance of some half-dozen fatal cases,’ reported the Allied scientists, ‘political prisoners might have been used in these experiments.’¹⁷

They might indeed. Although thousands of files on chemical warfare were destroyed by the Nazis between 1944-5, enough survived to show that with the start of the mass-extermination programme in the middle of the war, drastic experiments using lethal agents had begun to be carried out directly on human beings. At Natzweiler Concentration Camp, for example, in 1943, Professor Wimmer of the University of Strasburg ‘contaminated the forearms of twelve habitual criminals’ with mustard gas.

Each of the victims was photographed daily; three of them died. Later in the same year at Natzweiler, a second Strasburg scientist, Professor Picker, carried out tests on a further ten ‘habitual criminals’, exposing them in gas chambers for periods of three minutes at a time to ever-increasing concentrations of phosgene.¹⁹

Three scientists, led by SS Oberfuhrer Dr Mrugowsky, tested poison bullets on ‘five persons who had been sentenced to death’. The chemical was aconitine, a substance closely related to the nerve gases, which had already been considered as a possible agent by the British and Canadians. Mrugowsky’s account of the experiment, stamped top secret and dated September 1944, was sent to the Reich-Surgeon of the SS:

Tabun and sarin were also almost certainly tested on the inmates of the concentration camps. As the British investigators put it at the end of the war: it was extremely unlikely that the Nazi leadership ‘would have agreed to the diversion of considerable effort, in difficult circumstances, to the production of a chemical warfare agent which had not been shown unequivocably to be capable of killing men.’²¹

The experiments on human beings were not the isolated acts of a handful of SS sadists. After the war, Baron Georg von Schnitzler, a leading Nazi supporter and a prominent member of the board of IG Farben, swore that Ambros and other board members were aware of what was happening. British Intelligence reported that one of the IG Farben directors was said to have ‘justified the experiments not only on the grounds that the inmates of concentration camps would have been killed anyway by the Nazis, but also on the grounds that the experiments had a humanitarian aspect in that the lives of countless German workers were saved thereby.’²²

Most of the scientists working on poison gases loudly protested that they knew nothing of the experiments. Their denials were frequently unconvincing: some certainly had proven links with the SS. As the Allied interrogators drily observed, ‘The profession of such complete ignorance, advanced with wholly unnecessary vehemence left us with some doubts regarding their veracity.’²³

In the ‘night and fog’ of Hitler’s Germany, where any slight suspicion of disloyalty might lead to arrest by the Gestapo, few scientists seem to have had the will to resist such perversions of their profession.

By the end of 1944, Germany had a formidable nerve gas arsenal dispersed around the country. Poison gas shells were stored at Krappitz in Upper Silesia; others were said to have been hidden in old mine shafts in Lausitz and Saxony. In all, the various top secret munitions dumps contained around 12,000 tons of tabun – 2,000 tons loaded into shells, 10,000 into aircraft bombs.

As greater and greater tonnages of nerve gas weapons were stockpiled, the temptation to use them was correspondingly increased. Hitler himself – wounded by mustard gas in the First World War – was known to have a marked aversion to using chemical weapons: Raubkammer was the only major military trials ground he never visited.²⁴ Nevertheless, as Germany’s military plight became more desperate he began to hope that the nerve gases – like the V-weapons and the Nazis’ prototype jet engine – would ultimately turn the war in his favour. Shortly before D-Day, in 1944, he boasted to Mussolini of secret weapons that would ‘turn London into a garden of ruins’ and referred specifically to a deadly new war gas being developed by German chemists.²⁵ At the same time, stocks of tabun were moved south into Bavaria in case – as was at one time planned – Hitler should leave the Führerbunker in Berlin and put up a last-ditch stand amid the natural fortresses of the Alps.

Three of the most fanatical Nazi leaders, Bormann, Goebbels and Ley, repeatedly urged Hitler to unleash nerve gas. Goebbels wanted to use it against British cities in revenge for the destruction of Dresden. Albert Speer, Minister of Armaments in the Third Reich, recalled a secret conversation with labour leader Robert Ley ‘by profession a chemist’ held in his special railroad car. Ley’s ‘increased stammering betrayed his agitation: “You know we have this new poison gas – I’ve heard about it. The Führer must do it. He must use it. Now he has to do it. When else! This is the last moment. You too must make him realise it’s time.”’ Speer remained silent.

By 1945 it would have been suicidal for Hitler to have embarked upon chemical warfare. Even though there were thousands of tons of tabun available, there were simply not enough bombers left to deliver it. If he had issued the necessary orders Speer, aware that Germany would court massive retaliation, was fully prepared to sabotage them. Already, according to his testimony at Nuremberg, Speer was going to great lengths to divert raw materials and supplies of intermediates away from Germany’s chemical warfare factories: a claim which was corroborated by Karl Brandt, the head of chemical warfare defence in Germany. According to Brandt, he, Speer, and General Kennes (Assistant Chief of the General Staff) ‘had an agreement that, if some order had been forthcoming to start gas warfare against the Allies, they would themselves ensure that the initiation would not occur, as they proposed to hold up transport of supplies.’²⁷

A year earlier, however, and things might have been very different. The British were so certain that the Nazis had no new gas that during the Allied landings in Normandy in June 1944, Montgomery left all his troops’ anti-gas equipment behind in England; none of his men even carried gas masks.²⁸ Used against the fragile beach-heads, tabun might well have stopped the D-Day landings in their tracks. ‘When D-Day finally ended,’ wrote General Omar Bradley after the war, ‘without a whiff of gas, I was vastly relieved. For even a light sprinkling of persistent gas on Omaha Beach would have cost us our footing there.’ Gas, in Bradley’s view, could have ‘forced a decision in one of history’s climactic battles’.²⁹ With the extra six months that such a successful attack might have brought him, Hitler’s V-weapons might have seriously crumbled British commitment to the war; at the same time, the absence of the long-promised second front could have led Stalin to seek a separate peace. Had Hitler ordered its use, tabun might have altered the course of the war.

The reason he failed to do so probably had much to do with a conversation at the Wolf’s Lair, his headquarters in East Prussia, in May 1943. After the collapse at Stalingrad, both Speer and his chemical warfare expert, Otto Ambros, were summoned to a special conference by Hitler to discuss using gas to stem the Russian advance. Ambros began by saying that the Allies could out-produce Germany in chemical weapons. Hitler interrupted to say that he understood that might be true of conventional gases – ‘but Germany has a special gas, tabun. In this we have a monopoly in Germany.’ Ambros shook his head. ‘I have justified reasons to assume that tabun, too, is known abroad.’³⁰ According to Ambros, the essential nature of tabun and sarin had been disclosed in technical journals as long ago as 1902, and like many other German scientists he could not believe that the chemical warfare experts of Porton Down or Edgewood Arsenal had failed to develop them. Whether Ambros genuinely believed that the Allies had their own nerve gases, or whether he was merely trying to put off Hitler, the result was the same: Hitler turned on his heel and abruptly left the meeting. From that moment on, no matter how tempted he felt to use his secret gases, Hitler had always to balance in his mind the conviction of his scientists that the Allies had them too.

Had he known how flimsy the evidence was which supported these convictions he might have thought again. Nazi scientists, for example, read great significance into the fact that references to compounds related to nerve gases suddenly ceased to be mentioned in American scientific journals at the beginning of the war. They correctly deduced this was a result of censorship by the US authorities. What they did not know was that this was to protect the secrecy of the insecticide DDT then under development, not the secrecy of any new war gas. In other words, the Führer had been misled. Neither the Americans nor the British possessed a chemical weapon remotely capable of matching nerve gas.

Although it is generally the British who are hailed as the masters of secrecy and deception in the Second World War, the Germans must take a great deal of credit for the skill with which they deceived the Allies over nerve gas. It was one of the greatest secrets of the Third Reich, known only to a handful, and it was protected by labyrinthine security measures. Both the main nerve gases were given code names. Tabun was initially known as ‘Le 100’, then as ‘Gelan’, then as ‘Substance 83’; sarin as ‘Stoff 146’. Just as the Allies code-named the atomic bomb ‘Tube Alloy’ after a relatively innocuous war material, so eventually the nerve gases came to be known respectively as ‘Trilon 83’ and ‘Trilon 146’ after a common German detergent.

All the chemicals needed in the manufacture of nerve gas were transported under false names, names which were often changed a second or third time on arrival at their destination. The shipments were recorded in cipher in the so-called ‘Black Book’, a volume the size of a warehouse ledger, an inch and a half thick. At the end of the war it was secretly buried by the Nazis.

The result was records which would be largely unintelligible if captured. Even senior scientists were kept in ignorance of the various stages of nerve gas manufacture; they knew the details only of the particular part they worked in. Schrader himself was barred from certain vital areas of research. In Nazi Germany even the most intellectually curious were too intimidated to ask questions. ‘It was,’ concluded an Allied report at the end of the war, ‘safer to know little… Many of the technically-trained plant operators wore “blinkers” and dared allow their gazes to sweep only in the most restricted arc.’³¹

By such methods the Germans kept the secret of their nerve gases intact for more than eight years – one of the greatest triumphs of Nazi counter-espionage. The security precautions were breached only once, by complete accident, and so successful had the Nazis been in disguising the existence of tabun, that the British apparently refused to believe what they heard.

Throughout the war, unsubstantiated rumours did circulate between Washington and London of a new German poison gas. In 1941, senior United States and British chemists held a series of talks. Did the Americans, the British asked, believe in rumours of a new Nazi gas? They Americans said that they did.

The intelligence coup which should surely have finally convinced the Allies came two years later. On 11 May 1943, the British Army in Tunisia captured an important German prisoner. The man – whose name does not appear in the official records – was a chemist from the main Nazi chemical warfare laboratory at Spandau. He told the British everything he knew of a super gas called ‘Trilon 83’. The information was passed back to London by MI 19 (the branch of Military Intelligence responsible for the interrogation of prisoners) where it formed the basis of a ‘Most Secret’ report dated 3 July 1943.³³

The unknown informant told of a ‘clear colourless liquid with little smell’ which ‘cannot be classed with any of the other war gases as it is a nerve poison’ causing the eyes to shrink ‘to a pinhead and asthma-like difficulties in breathing. In any heavier concentrations death occurs in about a quarter of an hour.’ The prisoner, continued the report,

The chemist passed on details of the chemicals involved in manufacture and advice on defensive measures. All his information, advised the report, ‘may be classified as reliable’. Twenty-five copies were produced and circulated throughout Whitehall and Porton. Astonishingly, nothing happened.

The failure to act on the MI 19 report is all the more remarkable considering that the British, in their development of DDT, had tested compounds similar to tabun as potential war gases. They actually had a small production plant making a chemical called ‘PF-3’ which had similar effects on the body to tabun. Nerve gas had been accepted as a theory. Now, faced with the evidence that the Nazis had turned it into a workable weapon, the men at Porton chose to dismiss it. While Germans stocks of tabun mounted, they continued to concentrate their energies on time-consuming and futile attempts to produce a better version of mustard gas.

April 1945 was Porton’s moment of truth. A German ammunition dump was captured and a mysterious shell shipped back to the United Kingdom. Gingerly dismantled with the help of a nearby American field laboratory, the scientists discovered Hitler’s secret weapon. It was a terrible shock. Thirty-five years later it is still a source of embarrassment. ‘The only time we were really caught with our trousers down,’ says one senior Porton man today.

In classic bureaucratic manner, Porton at once tried to shift the blame on to someone else: it was not their fault, but the result of a failure in intelligence. The dismantled shell, claims Porton’s internal history, ‘was our first intimation that the Germans had this gas… no Intelligence Report from the year 1937 when Germany started working on it as a war gas had given any tangible clue to its existence.’³⁴

This has remained Porton’s excuse ever since. The yellowing MI 19 report – discovered amid a pile of recently declassified Government documents entitled ‘Chemical Warfare Intelligence 1939–44’ – enables this part of the record at least to be set straight. The British were ‘reliably’ warned of the existence of nerve gas almost two years before the end of the war. If Hitler had decided to use tabun in 1944, the decision to disregard the report might have gone down in history as one of the costliest intelligence blunders of the Second World War. Thanks in part to the Allied chemists’ stubborn belief in their own superiority, Hitler’s secret weapon stayed a secret till the end.