War of Nerves

by Jonathan Tucker

  The Army Gas Protection Laboratory subjected all candidate chemical warfare agents to a battery of tests to assess their toxicity in laboratory animals; the effects of temperature, humidity, and precipitation; and the feasibility of protecting friendly troops. Only about 2 percent of candidates survived the preliminary screening process and were sent for field testing. Those that proved effective in field trials had to overcome a final hurdle: the development of an economical process for industrial-scale production, including the availability of raw materials. By the end of the process, less than 1 percent of candidate chemical warfare agents were adopted by the Wehrmacht.

  The testing and evaluation of Tabun, however, proceeded with remarkable speed. In late May 1937, field trials of the new agent began at the Army Proving Ground (Heeresversuchstelle) Raubkammer, north of the small town of Munster on the Lüneburger Heath. A fenced, roughly rectangular area covering seventy-six square miles of forest and scrub, Raubkammer (also known as Munster-Nord or Munsterlager) had been built originally as a troop exercise area and had later been expanded for the open-air testing of chemical warfare agents. The entrance gate was flanked by two giant pillars, each surmounted with a Nazi spread eagle and swastika.

  The experimental station at Raubkammer had been designed with typical German thoroughness. Staffed by some five hundred scientists and technicians, it comprised a few dozen buildings in traditional German style, including well-equipped laboratories for chemical analysis and postmortem examination; animal facilities housing dogs, cats, guinea pigs, monkeys, apes, and horses; pilot production plants; and a large gas chamber in which animals could be exposed to toxic agents while scientists observed from a glassed-in balcony, as well as an administration building, barracks, and an officers’ mess. For testing decontamination methods, a half-mile stretch of road had been paved with a variety of surfaces, including cement, granite blocks, asphalt, and gravel.

  The field trials of Tabun at Raubkammer involved representatives from Division 9 and the Munitions Department of the Army Ordnance Office, the Army Gas Protection Laboratory, the Military Medical Academy, and the Air Ministry. Initial tests of Tabun-filled shells took place inside the Measurement House (Messhaus), a giant circular wooden chamber twenty meters high and thirty meters wide that was covered with scaffolding and had ventilator fans in the roof to remove the toxic gases. The inner walls of the building had numerous patches to repair holes made by flying shrapnel. During static firing experiments, an artillery shell charged with Tabun was detonated one and a half meters above the ground, and the concentration of the vapor cloud measured at various points within the chamber. The effects of the agent on tethered animals could be observed at the same time. These trials showed that the most effective way to disseminate Tabun was by using an explosive burster charge to break up the liquid agent into a fine mist of microscopic droplets, or aerosol, that would poison enemy troops by inhalation.

  Raubkammer also had a vast outdoor testing area (Übungsplatz), including a range on which chemical artillery shells could be fired from a distance of up to ten kilometers at an instrumented target grid that contained a concentric array of sampling devices. Near the impact zone, three concrete bunkers linked by telephone lines shielded the test personnel as they controlled the artillery fire. Although trials conducted on the firing range were more realistic than those inside the Measurement House, the outdoor results were difficult to interpret because of the large number of variables that had to be taken into account, including wind direction and velocity, air and ground temperature, and weather conditions.

  ON OCTOBER 27, 1937, Lieutenant Colonel Hermann Ochsner, the chief of the German Chemical Troops, prepared a memorandum for the Army General Staff in which he advocated the development of a new generation of chemical warfare agents. The first chlorine attack at Ypres in 1915 and Italy’s use of mustard agent during the invasion of Abyssinia, he wrote, had demonstrated the devastating effects of poison gas against an unprepared or unprotected enemy. Now, however, Western armies were equipped with gas masks and other defenses that deprived the existing chemical warfare agents of their effectiveness. “The successful surprise that was possible during the last war because of the total novelty of the chemical weapon can no longer be achieved,” Ochsner observed. “Back then, this means of warfare encountered a totally defenseless enemy. Today, the use of chemical warfare agents is generally known. Every modern army has gas masks that protect against all of the standard agents.”

  Another drawback of existing chemical warfare agents was that they all had distinctive odors that soldiers could be trained to recognize at low concentrations, enabling them to don their gas masks at the first whiff. Phosgene smelled like new-mown hay, mustard like garlic, lewisite like geraniums, and hydrogen cyanide like bitter almonds (although about 20 percent of people could not detect it). To achieve military surprise, Ochsner wrote, it would be necessary to develop new agents that had little or no odor, caused no sensory irritation, and were so toxic that one or two breaths could kill. In this context, he noted the recent discovery of a new substance that he called “Number 100,” a probable reference to Le-100 or Tabun. “This agent has been produced only in the laboratory and has been demonstrated to have good—indeed remarkable—effects,” he wrote. “An initial test in the open air failed, however. With respect to raw materials, the agent can be manufactured but requires as much chlorine as mustard gas.”

  Despite this mixed review, Tabun largely satisfied Ochsner’s criteria for high toxicity and difficulty of detection. The compound had a faint fruity odor but did not cause noticeable irritation of the eyes or lungs. Although standard gas mask filters protected effectively against Tabun, the difficulty of detection meant that troops could be exposed by surprise before they had time to don their masks. The new agent could also penetrate the skin, although absorbing a lethal dose in this manner could take as long as an hour. Contamination of soil, clothing, and equipment with liquid Tabun posed an additional hazard because the agent evaporated slowly, giving off toxic fumes. Even if low-level exposures were not sufficient to kill, they could incapacitate soldiers by causing severe visual impairment and an asthmalike shortness of breath.

  Field trials revealed certain limitations of Tabun as a war gas. Because the liquid agent was not particularly volatile, it was necessary to use a fairly large burster charge to transform it into a fine mist or vapor, yet the heat of the explosion destroyed much of the agent and reduced its effectiveness. The fact that Tabun vaporized more readily at higher temperatures and wind speeds made it more suitable for use during the summer months or in tropical climates.

  Schrader’s discovery of Tabun earned him some recognition from IG Farben. In November 1937, at Dr. Hörlein’s request, he was transferred from Leverkusen to a new laboratory at IG Elberfeld, where he continued his research under conditions of tight secrecy. Although the German Army proposed to give Schrader a contract to develop an industrial-scale production process for Tabun, Dr. Hörlein turned down this offer. IG Farben management was reluctant to get involved in chemical warfare for several reasons: the company was fully occupied with the development and manufacture of civilian products, chemical weapons were unlikely to generate much profit, and they might stir up negative publicity that would harm foreign sales. Accordingly, Schrader was told to concentrate on the development of agricultural insecticides, although he was allowed to dabble in his spare time on an improved production process for Tabun.

  In 1938, however, the IG Farben management had a change of heart about military work. Field Marshal Hermann Göring, the commandant of the Luftwaffe, asked Karl Krauch, the head of the company’s board of directors, to prepare a detailed plan for German chemical rearmament. Krauch’s report described poison gas in highly positive terms as “the weapon of superior intelligence and superior scientific-technical thinking. As such, it is called upon to be employed by Germany in a decisive manner, both on the front and against the enemy’s hinterland.”

  These ideas wo
n favor from Göring’s air-warfare strategists, who considered chemical weapons to be potentially decisive because of their ability to elicit terror and confusion in the enemy population. On August 22, 1938, Göring named Krauch his “Plenipotentiary for Special Questions of Chemical Production” under the Nazi Four-Year Plan. Because Germany had been forced to give up all of its chemical weapons factories after its defeat in World War I, they would have to be rebuilt from the ground up.

  In order to test Tabun-filled munitions under more realistic conditions than static detonation, the Army Proving Ground Raubkammer developed a new short-range firing apparatus called the “Vz Tower,” which began operation in November 1938. It consisted of a steel tower fifteen meters high, topped with a rotating platform on which were mounted a 105 mm light field howitzer and a 150 mm heavy howitzer. These guns fired chemical shells inside a circle with a radius of about fifty meters. To measure the concentration of the resulting gas clouds, a set of instruments was mounted on a miniature railroad car that ran along a track encircling the target area. Because of the configuration of the testing site, it was possible to take measurements regardless of the wind direction.

  In close collaboration with the Air Ministry, Raubkammer also tested 250-kilogram aerial bombs containing 85 kilograms of Tabun. Dropped from aircraft, the bombs exploded on impact with an instantaneous or delayed fuse. These tests showed that about 25 percent of the agent remained in the bomb crater, while the rest was converted into a vapor cloud that traveled about 100 meters downwind, creating a lethal zone of 3,000 to 5,000 square meters. Although spraying Tabun from a low-flying aircraft was a more effective means of dissemination, the Luftwaffe rejected this approach because it would expose the aircraft and crew to hostile ground fire.

  Field testing of Tabun was extremely hazardous and resulted in hundreds of injuries requiring medical attention. Even trace amounts of the agent, adhering to clothing, equipment, or the fur of dead animals, were sufficient to cause harmful exposures when masks and respirators were removed. Most cases of Tabun poisoning were mild, resulting in disturbances of vision and breathing that faded after a few days, but a few individuals were affected more severely.

  Physiologists at Raubkammer also deliberately tested low doses of Tabun on human volunteers, mainly officers, clerks, employees, laborers, and students from the Army Gas Protection Laboratory, who received a small financial incentive to participate. By providing useful information about the physiological effects of the agent in humans, these experiments enabled the Military Medical Academy in Berlin to develop antidotes. To counteract the effects of Tabun poisoning, physicians administered injections of atropine and the related drug scopolamine, which was safer but worked more slowly. Atropine, extracted from the deadly nightshade plant (Atropa belladonna), produced physiological effects that were diametrically opposed to those of Tabun. Whereas the nerve agent slowed the heartbeat, constricted the pupils, and stimulated the salivary glands, atropine increased the heart rate, dilated the pupils, and dried out the mouth. Indeed, the herbal source of atropine was known as “belladonna” because women had used it for centuries as a beauty aid, to enlarge their pupils.

  Meanwhile, working in his laboratory at Elberfeld, Schrader developed a new family of insecticides by replacing the cyanide group in Tabun with a fluorine atom and adding a phosphorus-methyl bond. On August 2, 1938, Schrader and Kükenthal filed a patent application for this class of compounds. (The patent was classified and was not published until September 1951.) Although all molecules of this type caused toxic effects in insects and animals, the various analogues differed considerably in potency. Lacking a theoretical explanation for why some structural variants were so much more potent than others, Schrader conducted his development work on a trial-and-error basis.

  Toward the end of 1938, Schrader synthesized an organophosphorus compound containing fluorine whose toxicity against insects proved to be “astonishingly high.” He gave a sample of the new substance to Dr. Gross for testing in a variety of warm-blooded animals. When the compound was injected into guinea pigs, a dosage of only 0.075 milligram per kilogram induced convulsions and rapid death. Inhalation tests also showed that the new substance was five to ten times more toxic than Tabun in dogs and twice as toxic in monkeys, ruling out its use as a commercial insecticide.

  In early 1939, Dr. Gross sent his toxicology report to the German War Office, along with a sample of the fluorine-containing compound, which the Army code-named “Substance 146.” Field testing at Raubkammer showed that the new agent was considerably more stable than Tabun and less likely to be destroyed by the explosion of an artillery shell or bomb. It was almost completely odorless, making it extremely difficult to detect, and it evaporated readily, increasing its potential utility on the battlefield. In June, Schrader traveled to Spandau Citadel in Berlin to deliver a presentation on Substance 146. The Army Gas Protection Laboratory assigned a large team of chemists to study the new agent and develop a simplified manufacturing process.

  At the same time, other Army chemists at Spandau were synthesizing Tabun in small lots of about one kilogram while attempting to scale up to larger batches. After several false starts, these pilot studies led to marked improvements in the manufacturing process. In February 1939, the experimental production of Tabun in 30-kilogram lots resulted in good yields and a product that was 90 percent pure. The next step was to develop a pilot plant with a batch capacity of 400 kilograms. Because it was not feasible to build such a facility at Spandau, the Army decided to locate it in the experimental station at Raubkammer. Known as the “Vorwerk Heidkrug,” the Tabun pilot plant was disguised as a government farm building.

  In a memorandum to the Army General Staff dated June 28, 1939, Colonel Ochsner argued that the production of chemical weapons would conserve iron and other strategic materials, and that new agents such as Tabun were a major military asset. Chemical attacks, he wrote, should be carried out “on a very large scale against the enemy hinterland by air strikes, especially against industry concentrations and large cities.” Such massive use would “overwhelm the enemy’s medical facilities with a flood of sick and injured” and terrify the civilian population. “There is no doubt,” Ochsner concluded, “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.”

  Despite the arguments by Ochsner and other advocates, Hitler showed little interest in chemical warfare and did not even visit the Raubkammer proving ground. Having been gassed during World War I, he had a strong aversion to such weapons and did not contemplate their use except for retaliation. Nevertheless, the Army Ordnance Office moved forward with preparations for the large-scale production of chemical agents. On August 5, 1939, General Walther von Brauchitsch, the commander in chief of the Army, approved the procurement of a stockpile of Tabun. This decision had been complicated by the fact that Substance 146 appeared to be significantly more effective than Tabun, but roughly two more years of development work would be required to bring the new agent to the point of large-scale production.

  To construct the Tabun production facility, the Army decided to hire a commercial contractor, and the obvious choice was IG Farben. Not only had one of its scientists invented Tabun, but the company manufactured all of the necessary chemical ingredients and its depth of expertise was unparalleled. The Army therefore asked IG Farben executives to draw up preliminary estimates for a factory capable of producing 1,000 metric tons of Tabun per month.

  ON SEPTEMBER 1, 1939, only a month after the German Army’s decision to manufacture Tabun as a standard chemical warfare agent, the Wehrmacht invaded Poland, plunging Europe once again into the inferno of war. On September 7, the Army Ordnance Office summoned three members of the IG Farben board of directors—Heinrich Hörlein, Fritz ter Meer, and Otto Ambros—to Berlin for a meeting. The officials present included Division 9 chief Colonel Siegfried Schmidt and representatives from the Procurement Division, the Army High Command, an
d the Army Gas Protection Laboratory.

  The two sides sat down across a conference table. Dr. Hörlein had sharp, rather sinister features and wore a pair of round glasses with black rims. Ter Meer, the chairman of IG Farben’s Technical Committee, had a large rectangular face, with dark hair slicked back from his broad forehead and a stern gaze. Ambros, the youngest of the three executives, wore a finely tailored suit, and his lean features and intelligent eyes radiated confidence and authority. After earning a doctorate in chemistry in 1926, at the age of twenty-five, Ambros had joined the IG Farben plant in Ludwigshafen. Four years later, he had been sent to Sumatra for a year to study the chemistry of natural rubber, and by 1935 he had become IG Farben’s leading expert on synthetic rubber, or Buna. Three years later, he had continued his meteoric rise through the company ranks by joining the board of directors, and he now managed eight of the company’s chemical plants.

  The Army officials opened the meeting by demanding IG Farben’s full cooperation with the war effort. “The production of poison gases will be essential,” Colonel Schmidt declared, “and IG Farben and other firms must do their part for the Fatherland.” The three executives pledged to perform their patriotic duty. As the Army had requested, they provided cost estimates for the construction of two chemical weapons–manufacturing plants, one for mustard and the other for Tabun. The Tabun plant would have a production capacity of 1,000 metric tons per month and the potential to expand to 2,000 tons per month if necessary. At a follow-up meeting on November 7, 1939, the IG Farben executives accepted a preliminary set of instructions and signed an oath of secrecy. The production contract was finalized in early December, and two weeks later the Army Ordnance Office issued a preliminary “order to proceed.”

  To operate the chemical weapons plants, the IG Farben board of directors established a new subsidiary called Anorgana GmbH with 100,000 reichsmarks of working capital. They named Otto Ambros as the managing director. Anorgana was secretly financed and controlled by a Wehrmacht holding company called Montan Industriewerke, and Anorgana’s board of directors consisted of three representatives from Montan and three from IG Farben. The reason for this byzantine organizational structure was to protect IG Farben’s financial interests and conceal the company’s involvement in chemical weapons production. Over the next few weeks, IG Farben’s director of construction tried to find a suitable location for the Tabun plant in a remote portion of the Reich, far from populated areas. On December 30, 1939, after scouting several options, he recommended a site near Dyhernfurth, a small town and castle on the Oder River 40 kilometers northwest of Breslau, in the eastern province of Silesia.