by Sam Kean
He began by outlining a history of the topic, but a colleague interrupted. Don’t bother, he said, we know all this. Heisenberg was one of those easygoing lecturers who didn’t mind interruptions, so he shrugged and skipped ahead. Berg noted that he paced as he talked, his left hand thrust in his jacket pocket. And despite the esoteric topic, Berg strained for any hint that Heisenberg might be betraying more than he realized. Do those equations relate to fission somehow? Is scattering important for chain reactions? At one point Heisenberg’s gaze lingered on the unibrowed stranger for several seconds; they might well have locked eyes. “H. likes my interest in his lecture,” Berg wrote.
No matter how hard he strained, though, Berg couldn’t decipher the equations. It all seemed like innocuous physics, but how could he be sure? Was he missing something? Doubt began gnawing at him, and his mind inevitably circled back to the most famous discovery of the man now pacing the stage. Berg scribbled in his notebook, “As I listen, I am uncertain—see: Heisenberg’s uncertainty principle—what to do.”
Meanwhile, the physicists in the room remained oblivious to Berg’s torment, focused on the equations. “Discussing math while Rome burns,” Berg wrote. “If they [only] knew what I’m thinking.” In truth, Berg himself didn’t know what to think. Failing to act could hand Hitler the Bomb, and Europe with it. (So do I shoot and potentially save the world?) Then again, could he really shoot a man without hard evidence—especially knowing that he’d sacrifice himself in the process? He could feel the gun heavy in his pocket, but as Heisenberg droned on, that other piece of OSS gear, the L-pill, must have weighed more and more heavily on his mind.
This private torture continued for two and a half hours. And in the end, uncertainty made up his mind for him. When the lecture ended, he still couldn’t bring himself to shoot.
Afterward, the score of physicists broke into small groups to chat, and a few rushed the stage to talk to Heisenberg. Berg took the opportunity to introduce himself to Flute, reciting a prearranged code phrase, “Doctor Suits sends his regards from Schenectady.” Berg also passed along a gift from Allied intelligence—a vial of heavy water. The two spies quietly arranged to meet later that night in Flute’s office.
Berg then crept close to the scrum around Heisenberg to eavesdrop, pretending to study the equations on the blackboard. Might Heisenberg let his guard down now, brag about something? No. After a bit of chitchat, a few old chums whisked Heisenberg off to dinner at the famous Kronenhalle café, leaving Berg behind in the freezing lecture hall. Having nothing to do, he skulked off to meet Flute—emotionally wrung out and still uncertain whether he’d done the right thing.
Heisenberg, meanwhile, was in high spirits at dinner. The lecture had gone well, he was surrounded by friends, and a newspaper story about the new German offensive left him so thrilled that he read it aloud at the table. “They’re coming on now!” he marveled. Oblivious as ever, he failed to notice that his hosts were mortified.
Later that week Berg got a second chance. Flute was holding a small dinner party in Heisenberg’s honor, and Berg hoped that, away from the seminar room, in a relaxed atmosphere with wine and food, some unguarded remark would betray the status of the German nuclear bomb program.
As with his lecture, Heisenberg put stipulations on the party, telling Flute that politics and the war were verboten topics of conversation. He had good reason for doing this. In the few days since he’d crowed over the newspaper article, the Battle of the Bulge had turned against Germany. The Wehrmacht certainly hadn’t been crushed, but the fighting had deteriorated into a yard-by-yard struggle amid snowdrifts and icy streams—exactly the sort of long slog that a depleted Germany could never win. Heisenberg’s grand, improbable dream—for a stalemate that would somehow both discredit the Nazis and keep the Allies out of his homeland—seemed less and less likely. Moreover, in the nest of spies and informants that was Zurich, he didn’t want to talk politics among strangers. Even at this late stage of the war, “defeatist remarks” could get you shot in Germany.
Flute agreed to Heisenberg’s demands, but as soon as the party started, Heisenberg realized the futility of this promise. Even if Flute stayed quiet, he had no control over his guests, several of whom cornered the physicist to pelt him with questions. Berg sidled up to listen, and it was ugly from the start. No one wanted to hear Heisenberg’s rationalizations, and when he began whining about how the world was demonizing the good people of Germany, the other guests jumped down his throat, reminding him who exactly had started this war. They also scoffed when Heisenberg claimed to know nothing of Jews and other undesirables disappearing from Germany in large numbers. (In truth he almost certainly knew that his precious uranium came from processing plants that employed female slaves.) The guests backed down only when he stoked their fears about the Soviet Union: he argued that Germany was the one bulwark between civilized Europe and the hordes of Red barbarians eager to overrun it, a scenario that frightened your average Swiss even more than a German invasion. Heisenberg being Heisenberg, however, he managed to swallow his foot one last time near the end of the interrogation. Someone said, “You have to admit the war is lost.” Heisenberg sighed and said, “But it would have been so good if we had won.”
Heisenberg no doubt left the party exhausted and alone; all the residual joy from the lecture a few days earlier had dissipated. But as he donned his coat and stepped outside to walk home, someone joined him, someone he recognized from the lecture: the Swiss physics student with the heavy eyebrows. They were going the same way, it turned out, so he and Moe Berg—gun in pocket, pill in pocket—slipped off together.
As they walked, Berg pestered the physicist with questions. Drawing on his lawyerly training, he made several leading statements as well, trying to draw Heisenberg out. He complained about how boring Zurich was, saying that he’d give anything to be in Germany right now, where you could really fight the enemy. Heisenberg muttered that he disagreed but didn’t elaborate.
As they stalked the dark streets of Zurich, Berg continued to press and Heisenberg continued to parry: years of living under Hitler had conditioned him to guard his opinions, and he answered the “student’s” questions as vaguely as he could without being rude. Still, he had no inkling that this man was prepared to shoot him; even a jest, an ironic comment taken the wrong way, could have fatal consequences. Berg, meanwhile, had a perfect opportunity to carry out the execution. They were walking alone, at night; he easily could have ditched the gun and fled. So why not shoot Heisenberg, just to be safe?
In the end, uncertainty triumphed again: Berg simply couldn’t do it. The two men parted at Heisenberg’s hotel, and when Heisenberg turned his back one last time, Berg made himself walk away. Heisenberg entered the lobby and put the encounter out of his mind. Berg never could.
Heisenberg left Zurich the next day to spend Christmas with his family in Germany; he had toys for his children and skin cream and a sweater for his wife. To cut down on smuggling, Germany had banned the importation of certain goods from Switzerland, so Heisenberg had to pull the woman’s sweater over his shirt at the border and pretend it was his.
Berg continued to poke around Zurich for the next week, and he did pick up some choice bits of intelligence from Flute. These included claims of a “supercyclotron” in Germany that could separate fissile isotopes much faster than any previous method—exactly the sort of “kitchen sink” apparatus Oppenheimer had warned about. Berg also confirmed earlier reports on the whereabouts of Heisenberg’s new lab, as well as his family cottage south of Munich.
Despite the praise these reports won him, Berg still felt tortured by doubt as 1944 came to a close. Fate had thrown him two chances to take out Germany’s top nuclear scientist, and he’d watched both pitches go by. Would he come to regret his prudence? Would the world?
If Berg couldn’t act, though, his sometime nemesis Boris Pash would have no such qualms—no such uncertainty—about the need to render Werner Heisenberg hors de combat.
PART VI
1945
CHAPTER 55
Operation Big
The spring of 1945 saw the last days of World War II in Europe. But for a roving unit like Alsos, the chaotic end of the war was in many ways the most dangerous time.
Allied armies poured into Germany after the Nazis lost the Battle of the Bulge, and Alsos finally entered the country in March. In contrast to the jubilant Parisians, German citizens met them with hard stares and tried to undermine their progress. Sometimes this was merely annoying. Boris Pash once asked two German villagers which road to take to get to Heidelberg. Each man pointed—in a different direction. Pash growled that he was going to seize both of them, take each road in turn, and hang the one who’d lied. They blanched and pointed to a third road, muttering that they’d misunderstood the question. Other times Germans came within a hair of murdering an Alsos member. A sniper put a hole in the windshield of one vehicle, and a few weeks later Samuel Goudsmit—who was standing up in a jeep doing 50 miles an hour at the time—was nearly scalped when his head struck a wire strung across the road. Only his steel helmet saved him.
Despite these dangers Pash pushed his troops relentlessly. Stories abound of Alsos folks jumping onto jeeps and racing off to some recently liberated lab with nary a toothbrush or a change of socks. When one fellow ran out of skivvies, rather than waste time returning to base, he liberated a pink pair of women’s long underwear from a nearby home and trimmed them strategically to fit him. (This earned him some snickers, but they had to be more comfortable than the army’s standard-issue long underdrawers, which according to one account were “so stiff that you didn’t have to hang them up; you just stood them up on the floor beside your cot.”)
Thanks to relentless Allied bombing campaigns, large swaths of Germany lay in ruins. At some labs the Alsos crews were more archaeologists than anything, digging documents and equipment out of rubble. In one cratered-out city a physicist named Smyth recalled driving past a few gutted buildings and seeing water pipes “almost tied into knots by the violence of the explosions.” In another city he noticed roses blooming unaccountably early that spring on a grassy strip of median. It seemed a poetic moment—renewed life amid the destruction—until he realized that the heat of a few smoldering buildings nearby had simply tricked the bushes into thinking it was summer. So much for metaphor.
On April 11, Lightning-A reached the central German town of Stadtilm, where Pash encountered the rowdiest mob he’d seen since the Antwerp zoo. The town had virtually no electricity, and refugees and escaped prisoners were running amok. One gang found a railroad car full of industrial alcohol and tapped it. Two people died and one more went blind before Pash prevailed on the local burgermeister to drain it. After the chaos subsided, Pash learned that Uranium Club founder Kurt Diebner had been stationed in town but had slipped away just hours before.
Eventually Alsos established a new headquarters in Heidelberg, taking over a picturesque estate. From their ragtag start in Italy, the mission had grown into a force of one hundred plus troops—enough for Coach Pash to organize nine-on-nine baseball games on the grounds, even hurling a few innings himself. Amid the games, however, Alsos had some serious decisions to make. The United States, United Kingdom, Soviet Union, and France had agreed in February 1945 to partition postwar Germany into four zones, each one occupied by a different conquering power. Unfortunately, one top Alsos target lay inside the Soviet zone—a huge stash of uranium at Stassfurt, ninety miles southwest of Berlin. Pash wanted nothing more than to raid the stash and stick it to the Russians, but he’d recently been feeling some heat from Washington, having been threatened with three separate court-martials by then for his freewheelin’ ways. So before he risked angering the Soviets and causing a diplomatic incident, he sent a message to General Omar Bradley soliciting his thoughts. Bradley’s response? “To hell with the Russians.” That meant yes, and Lightning-A rolled out in mid-April.
A few months earlier, in Belgium and Toulouse, Pash had seized a few dozen tons of uranium. In Stassfurt he found more than a thousand tons, 2.2 million pounds total. The problem was, most of it was stored in small barrels that had cracked or split, spilling radioactive ore all over. Even worse, the Russians were already on the march and were making straight for the area.
Refusing to concede defeat, Pash summoned two military trucking units to the site. Then he rushed over to a nearby factory that made barrels and heavy-duty bags for packaging fruit and persuaded the workers to fire up their machines. They cranked out several thousand containers over the next few days, then pitched in to help stuff uranium inside. Despite occasional shells and gunfire, they managed to fill 260 vehicles and clear out every last ounce of ore in less than a week. General Groves later called the heist one of the biggest reliefs of the war for him: the vast majority of the missing Nazi uranium was now accounted for.
The trucking troops didn’t know what they were hauling away, of course, only that the barrels were unaccountably heavy. Because one of the Alsos officers was named Calvert, some speculated they were transporting whiskey. Others swore they were stealing Nazi gold. The Soviets had no such illusions. When technical crews arrived in Stassfurt a few weeks later, they discovered the heist and were furious. Boris Pash’s little caper, in fact, served as one of the opening salvos of the Cold War.
With the uranium ore secure, Alsos turned its attention to hunting down the Uranium Club—an urgent task, since the Russians were also eager to lay hands on German scientists. In Heidelberg, one Alsos unit had already snagged the lovelorn Walther Bothe, whom Goudsmit (recently returned from rest leave) interrogated at his lab. Bothe was the first German prisoner Goudsmit knew personally, and they shook hands upon greeting, despite the U.S. army’s rules against fraternizing with the enemy. With boyish pride Bothe showed off his cyclotron, which at long last had sputtered to life. Goudsmit tried to smile, but he found the scene pathetic: the United States had a score of working cyclotrons by then, any number of which were far more powerful than Bothe’s toy.
Most club members proved harder to track down. One complication was that the Black Forest region where they’d fled to happened to lie within the French zone of occupation, so politics once again came into play. Pash at first suggested a deadly-hombre mission that involved parachuting into the area ahead of the French army and seizing all the scientists. Nothing ever came of this, but with the German resistance crumbling and the French army making good progress for once, Alsos had to hurry. For a while American officials seriously debated carpet-bombing the advancing French troops to slow them down. Eisenhower’s chief of staff finally had to put the kibosh on that: “We cannot bomb the French,” he said with a sigh, “much as I would like to.” Only one option remained: Lightning-A would have to race south and sweep in ahead of the French troops. They called the plan Operation Big.
Luckily for Pash, many of the advancing French battalions had higher priorities than defeating Germany. Stuffing their pockets with loot, for instance, or hunting down Vichy traitors. A few avant-garde units were fast approaching the Black Forest, however, and Pash had to dip into his bag of ruses to get around them. At one point on the way south, Lightning-A encountered a formidable German barricade—thirty massive logs strewn across the road, with several more driven into the ground like pikes. They had no choice but stop and clear them. Meanwhile, a French unit had skirted the barrier by going off-road, dropping down into a nearby streambed. With their head start, they stood a good chance of opening up an insurmountable lead on Alsos.
Unfortunately for the French, the warm spring weather had started to thaw the streambed; Pash called it some of the swampiest, ooziest ground he’d ever seen outside an Alaskan bog. The French vehicles could still make their way along, provided they didn’t slow down. So Pash waited until the convoy had reached the soupiest part, then yelled out for the leader of the column, a major, to dismount and stand at attention. The major ignored him, so Pash scrambled down the slope from the road, screamin
g in French, “When a colonel speaks to you, you assume attention!” Soldierly instinct won out over common sense, and the major stopped his car and obeyed. Splashing up to him, Pash introduced himself and was the soul of courtesy thereafter, asking all sorts of thoughtful questions about the man’s trip so far. The major answered Pash—he had no choice—but his eyes kept darting up to the road, where Alsos engineers were making short work of the barricade. Meanwhile the major’s car had sunk up to its axles in muck, and a similar fate befell every vehicle stopped behind him. Pash continued to blather until Alsos cleared the roadblock. Then he wished the major a bonne journée, and raced off cackling.
This put Alsos among the new avant-garde, an enviable but dangerous position. In most villages in the region, the inhabitants had already given up, hanging pillowcases or sheets out their windows to signal surrender. But those white cloths sometimes concealed nests of SS troops, who had no compunctions about faking a surrender and opening fire. Moreover, bands of Werwolfen—self-proclaimed Nazi “werewolves”—continued to fight for their Führer. Even with the war lost, they wanted to ambush and kill as many enemy soldiers as possible.
Lightning-A’s top priority in the region was reaching Haigerloch, the village with the cave where Heisenberg was building his final Uranium Machine. One historian compared the town to “the setting of some extravagant Wagner or Weber opera,” with cobblestone streets and houses dating back to the 1100s; it was nestled against an eighty-foot limestone cliff with a stone castle and white baroque cathedral at the top. The landscape surrounding the town was just as magical, with rolling farmlands and fields; it was famous in springtime for its lilacs.