Diana Preston - Before the Fallout

In late March 1945, following swiftly in the wake of Allied troops, the Alsos team crossed the Rhine, entered Heidelberg, and seized Walther Bothe’s institute, home of Germany’s only functioning cyclotron. Bothe, the scientist whose mistaken conclusions had convinced his colleagues that they needed heavy water, not graphite, as a moderator, was the first enemy scientist to be apprehended whom Goudsmit knew personally. Bothe shook Goudsmit’s hand warmly but refused to talk about his military work.

Moving on to Gottingen, Goudsmit met Morris “Moe” Berg, a former catcher for the Washington Senators and Boston Red Sox baseball teams, and now an American secret agent who had been involved in a scheme to capture, even to assassinate, Heisenberg. The idea of kidnapping Heisenberg had first been mooted in October 1942 when news of Heisenberg’s appointment as director of the Kaiser Wilhelm Institute of Physics some months earlier first trickled through to refugee scientists in the United States. Their respect for Heisenberg’s abilities had made them highly nervous of what he might achieve. After discussing the problem with Hans Bethe, Victor Weisskopf had sent to Robert Oppenheimer a three-page letter stating their concerns. “By far the best thing,” Weisskopf had suggested, “would be to organize a kidnapping.” He even volunteered to undertake the mission himself. Oppenheimer thanked him for his “interesting” letter, which he had submitted “to the proper authorities,” but told Weisskopf, “I doubt whether you will hear further of the matter.”

However, the idea had not gone away. In December 1944 U.S. special operations had sent Moe Berg to Zurich, where Heisenberg was to lecture, with a gun in his pocket and orders that if Heisenberg said anything suggesting that German scientists were close to making an atomic weapon, Berg was to shoot him dead in the auditorium. Berg had hung on Heisenberg’s words but heard nothing to convince him to fire his gun. Later, Berg engineered an introduction to Heisenberg and accompanied him on a long walk through ill-lit streets back to Heisenberg’s hotel, during which he badgered him with questions. Berg was a good linguist and spoke German well. Heisenberg, who had no idea his life was hanging on what he said, assumed the pushy stranger was Swiss. Unsurprisingly, he responded guardedly and again revealed nothing implying that Germany possessed a war-winning weapon. Indeed, Heisenberg seemed regretfully resigned to Germany’s losing the war. Berg allowed him to leave Switzerland unharmed.

Berg’s reassuring view of the relative poverty of the German nuclear capability did not distract Alsos from urgently tracking down German scientists and facilities. High on their list was Diebner’s German Army Ordnance fission project operating at Stadtilm, to which papers found in Heidelberg had alerted them. Immediately on hearing that Stadtilm was in Allied hands, Goudsmit flew there from Paris, only to discover that the Gestapo had whisked away Kurt Diebner and several trucks of equipment two days earlier. However, he got his first look at part of the German fission program: “It was located in an old school-house. The cellar of that place looked almost like a natural cave and seemed quite bombproof. It was there that our men found the few remaining physicists huddled together with their families.”

A few days later at the town of Celle, north of Hanover, the Alsos team discovered an isotope-separation laboratory hidden away by Paul Harteck in a parachute silk factory. Harteck himself had fled, but a brief examination of the centrifuge he had been developing satisfied Goudsmit that it “would have taken a hundred years” to produce sufficient quantities of U-235 for a bomb. Even more important, soon afterward, an Anglo-American strike force located the bulk of the uranium taken by the Germans from Belgium and seized it from under the noses of advancing Russian troops near Magdeburg. On 23 April 1945 Groves told the army chief of staff, General George Marshall, categorically that the risk of a German nuclear weapon was over.

That same day, Colonel Pash, rushing to get there in advance of French troops, reached Haigerloch. He feared attack by the “Werewolves,” a fanatical Nazi resistance group, but as he drove in, white pillowcases, sheets, and towels fluttered from every window. His men quickly found Heisenberg and von Weizsacker’s secret German laboratory. Pash later wrote that it was an “ingenious set-up” camouflaged and protected by “a church atop a cliff.” He found “a box-like concrete entrance to a cave” in the side of the cliff. Inside was “a concrete pit about ten feet in diameter. Within the pit hung a heavy metal shield covering the top of a thick metal cylinder. The latter contained a pot-shaped vessel, also of heavy metal, about four feet below the floor level.” It was, Pash realized, “the Nazi uranium ‘machine.’” In another chamber containing a series of cylinders he found a blackboard on which was chalked “Let rest be holy to mankind. Only crazy people are in a hurry.”

Leaving a team to photograph and dismantle the contents of the cave, Pash moved on to nearby Hechingen. The first thing he saw on entering Heisenberg’s office in the woolen mill chosen to house the Kaiser Wilhelm Institute for Physics was the surreal sight of a photograph of Heisenberg and Goudsmit taken in 1939 at Ann Arbor. Heisenberg, in Goudsmit’s view “the brains of the German uranium project,” was gone. However, Goudsmit, who arrived there soon afterward from Haigerloch, was able to begin interrogating some twenty-five captured scientists and technicians. They included von Weizsacker, who had quickly been apprehended, Karl Wirtz, one of Heisenberg’s key assistants in Berlin, and Erich Bagge and Horst Korsching, who had both been working on isotopic separation. Von Weizsacker objected that the latter were too junior and insignificant to detain. According to Goudsmit, he remarked, “What kind of selection is this?” Goudsmit had also taken Max von Laue into protective custody. He knew that von Laue had no direct connections with the nuclear work, but he respected him deeply and believed he should play a part in the reconstruction of science in postwar Germany.

Goudsmit learned from von Weizsacker that his final contribution to the German war effort had been to lower a sealed metal drum containing key research notes into a stinking cesspit. The drum was retrieved. So were three drums of heavy water and the uranium used in the Haigerloch reactor that Heisenberg had ordered to be buried. The Alsos team celebrated their success by consuming the contents of von Weizsacker’s wine cellar, which they had also discovered.

The Alsos team withdrew just before French Moroccan troops swept into Hechingen. Pash headed next for Tailfingen and Otto Hahn. Pash found Hahn and his entire staff assembled calmly in their laboratory. Hahn was extremely cooperative. As Pash recalled, he “unhesitatingly” produced a pile of scientific reports and volunteered his view that a nuclear bomb could not be built. Goudsmit took him too into custody.

In early May in Bavaria, the Alsos team caught up with Walther Gerlach and Kurt Diebner. They also finally captured their primary target, Werner Heisenberg. At 3 o’clock on the morning of Friday, 20 April, he had cycled out of Hechingen into the darkness, determined to reach his wife and children 1 20 miles away at Urfeld. He completed the journey, evading fire from low-flying Allied aircraft and equally dangerous groups of hard-line Nazis roaming the countryside shooting or hanging anyone they took it into their heads to suspect of disloyalty to the Fatherland. When, a few days later, Pash arrived to arrest him, Heisenberg’s initial reaction was relief. He later recalled he felt “like an utterly exhausted swimmer setting foot on firm land.” However, knowing that he had to leave his wife and children behind and fearing that the locals would treat them harshly if he was seen to cooperate, he begged Pash to make it look as if he was being arrested against his will.