by Sam Kean
PART IV
1943
CHAPTER 25
Secret Messages
British physicists had been trying to evacuate Niels Bohr from Denmark for years, partly for his own protection and partly to exploit his genius for the Allied war effort. To this end, a member of the Danish underground visited him at his home in Copenhagen in January 1943 with an offer to smuggle him out.
Wary of a trap, Bohr refused to consider the offer without written confirmation from the British. Perhaps a little elaborately, the agent relayed Bohr’s request by writing a letter, shrinking it onto microfilm, and concealing copies beneath the stamps of several postcards, which he mailed to a second agent in Stockholm. After peeling the microfilm off the stamps, this agent locked himself in a room and used a projector to magnify the message, which he then dispatched to the British.
As if trying to one-up the Danes, the British responded in even more elaborate fashion. In early February the Copenhagen agent received a phone call from a contact at a bank saying that someone had left a set of old iron keys there. After retrieving them, he clamped one of the keys—marked 229—into a vise and began filing it at a specific point. A sixth of an inch down, a tiny cavity appeared. Inside were three half-millimeter-square specks of microfilm. At this point he tied a kerchief around his nose and mouth to avoid accidentally sneezing or coughing and sending the specks flying. He then floated them out with water and read them with a 600-magnification microscope borrowed from a doctor friend. (All three specks held the same message, but some words inevitably got blurred during the shrinking process, and only by comparing all three versions could he make them out.) He passed the message to Bohr, then had Bohr bury the keys in his garden.
The message came from James Chadwick, the nuclear physicist who’d discovered the neutron years before. He knew Bohr well and begged him to come to England. “I have in mind a particular problem in which your assistance would be of the greatest help,” he wrote. (Charles Darwin, a physicist and the grandson of the naturalist, also solicited Bohr’s help.) Given Chadwick’s interest in neutrons, Bohr deduced that Britain had started an atomic bomb program.
But this news didn’t stir Bohr as deeply as you might expect. Bohr was the scientist who’d first discovered, back in 1939, that uranium-235 was the key isotope for fission: it alone drove nuclear chain reactions, not the vastly more abundant uranium-238. Cut off as he was in Denmark, he knew nothing of recent advances in uranium enrichment and therefore dismissed the idea of enrichment as fantastical. To make a single bomb, he famously declared, you’d have to turn your entire country into a factory. Consequently, the offer to work in England seemed futile: “I have to the best of my judgment convinced myself,” he wrote in his typically tortured syntax, “that in spite of all future prospects any immediate use of the latest marvelous discoveries of atomic physics is impracticable.” This response, naturally, was shrunk onto microfilm, wrapped in metallic foil, hidden in a false tooth in a courier’s dentures, and smuggled to England.
The British persisted in pleading with Bohr, and Bohr later passed along some rumors about German scientists buying up uranium and heavy water. But the British simply couldn’t dislodge the Great Dane from Copenhagen. Beyond the impracticable physics of nuclear bombs, Bohr also felt obligated to stay in Denmark and protect his fellow citizens. As with Heisenberg and Joliot, he felt his country needed him, and thanks in part to Bohr’s influence—and his underground resistance work—Denmark did enjoy relative freedom compared to other conquered countries in Europe.
In reality, however, Denmark owed most of its precious freedom not to resistance fighters like Bohr but to other factors. For one thing, the starving German populace needed the country’s beef, cheese, and butter. For another, the Danes had a kind of—if one can even say this—Nazi guardian angel in Berlin. This savior was Ernest von Weizsäcker, the second-ranking officer in the Reich foreign ministry and the father of the patrician physicist Carl von Weizsäcker. Weizsäcker père certainly participated in despicable deeds, but he had more humanity in him than most Nazis and had fond memories of Copenhagen from his days as a diplomat there. He therefore defied Hitler’s orders to round up and deport Danish Jews. Out of deference to his son, Weizsäcker also protected both Bohr and his physics institute from harassment.
Alas for Bohr, the elder Weizsäcker had grander ambitions than saving Denmark. After months of scheming, Ernest accepted an offer in March 1943 to become the Nazi ambassador to the Vatican. On paper this was a curious decision. Given his exalted position in Berlin, moving to the tiny papal state was a de facto demotion. It also played right into the hands of Weizsäcker’s boss, the odious Joachim von Ribbentrop. Like many top Nazis, Ribbentrop preferred to surround himself with toadies, and he happily bid adieu to the talented, humane Weizsäcker. But Ribbentrop never suspected his underling’s real motivation for leaving. Weizsäcker had grown disillusioned with Hitlerism, and as the Wehrmacht got bogged down in North Africa and Russia, he wanted to end the war quickly and with honor. Although puny in size, the Vatican had worldwide reach and outsized moral standing. (As a matter of fact, in one of the most head-scratching incidents of the war, Pope Pius XII broadcast a speech in February 1943 warning humanity about the menace of nuclear bombs. No one has ever quite figured out how he learned about this top-secret research so early.) As ambassador to the Vatican, Weizsäcker hoped to open secret negotiations between the Holy See and Italy, to convince the Italians to lay down arms. This would deprive the Reich of its strongest ally in Europe, at which point, he calculated, the Reich would quit the war as well.
All of this was treason, obviously. Had Ribbentrop caught even a whiff of it, he would have had Weizsäcker arrested and executed. But Weizsäcker thought the gamble worth taking and moved to Rome in April 1943. This would leave Denmark vulnerable, but ending a world war was a higher priority. Besides, the political situation in Denmark seemed stable. He saw no reason to worry about the fate of Niels Bohr.
CHAPTER 26
Operation Gunnerside
The Grouse team was indignant. Despite the Operation Freshman fiasco, the British Ministry of Ungentlemanly Warfare still wanted to take out the heavy-water plant at Vemork and needed the quartet’s help. A few days after the failed mission, they radioed the crew with orders to sit tight and make do, despite the approaching winter. “How? With what?” one commando remembered thinking. “We had no food left. We had nothing.”
You couldn’t say the weather on the plateau never changed—sometimes the blizzards blew in from the north, sometimes they blew in from the south—but it was always harsh. With no dry wood for fires, the Grouse team had to bundle themselves up in everything they owned: long underwear, stocking hats, sweaters, parkas, windproof pants, multiple pairs of socks and gloves. They still felt like frostbitten icicles, and they spent most nights shivering inside their sleeping bags. And as bad as the cold was, the hunger was worse. Aside from handfuls of oatmeal and other goods they had nothing left to eat, and they began breaking into nearby cabins to scrounge whatever they could—moldy turnips, cod-liver oil, fermented fish, even dog food. Finally they got so desperate for meat that one man risked stealing a sheep from a local rancher. He then made a succulent stew, letting it steep for hours. The very smell of it cratered their bellies. But in pulling the kettle off the fire, the weakened cook slipped on a reindeer pelt and spilled everything, flooding the dirty cabin floor. The men stared at their feet for a second—then dropped to all fours and started scooping and slurping. Halfway through the “meal,” one man joked about finding a hair in his soup, which in their delirium they found hilarious.
A few weeks later they’d even run out of humor. “What was the point of our suffering here in the mountains?” one soldier thought. “Was there any chance that [the sabotage mission] might succeed and that we might escape alive?” Confined to their cabin most hours, they were beyond stir-crazy by then, and the irritations of daily life—little arguments about whose turn it was
to cook breakfast or take out the trash—metastasized into full-blown rows. The only fresh game for miles was reindeer, and on the rare occasions they caught one, they devoured it down to the marrow, learning to relish even the eyeballs and lips (which tasted uncannily like chestnuts). They also wolfed down the half-digested lichen in the reindeers’ bellies, called gørr, their only source of vitamin C. All the while the bloody Brits kept telling them to sit tight. Operation Gunnerside was coming.
Gunnerside would follow the same basic plot as Freshman. Commandos would storm the Vemork power plant and destroy the heavy-water cells in the basement. But instead of thirty commandos, Gunnerside would employ a leaner, stealthier force of ten—the four Grouse men, plus six more who’d parachute in later. Their commander would be a tall, twenty-three-year-old explosives expert named Joachim Rønneberg, who looked thin to the point of being tubercular. And unlike the Freshman team, all ten soldiers would be Hardanger locals who knew the terrain and were expert skiers.
Apparently not superstitious, Rønneberg’s crew of six trained on the same wooden mockup of Vemork as the doomed Freshman commandos had. Because the British remained skeptical of Norwegian troops, the six had to work doubly hard to prove themselves, memorizing every entrance to the basement—doors, windows, utility shafts—and drilling relentlessly on placing explosives in the dark. They used half-pound plugs of Nobel 808, a burnt-orange compound that smelled like almonds; they got a feel for its strength by blowing practice holes in brick walls.
There was one risk they couldn’t mitigate, however, no matter how hard they drilled—the risk of reprisals. The Nazis discouraged native resistance in Norway by going biblical on Allied collaborators, punishing even their innocent friends and neighbors. In one coastal village west of Vemork, for instance, the local German commander had caught several people with bags of British baking flour the previous April; he suspected (correctly) that they’d received them in exchange for helping to sabotage some nearby sites. His investigation began with a Gestapo agent infiltrating the village disguised as a Bible salesman. He found enough evidence to justify a raid a few days later, during which the Nazis discovered more sabotage equipment, as well as caches of weapons. Having nothing to lose now (so they thought), a few underground fighters opened fired and killed a Nazi soldier. In response, the German commander burned down every house in the village and executed eighteen men. His rage unslaked, he then sunk every boat in the harbor, killed every domesticated animal, and shipped every last surviving inhabitant—from toddlers to toothless grandmas—to a concentration camp. Sic semper collaborators: he essentially erased the town from the map.
In using local Norwegian soldiers, then, Operation Gunnerside was gambling with the lives of every plant worker and villager near Vemork. But once again, fear of an atomic Reich trampled every other consideration.
The Gunnerside raid was originally scheduled for Christmas Eve 1942—an unexpected and therefore ideal night to strike. Instead of using gliders, the six additional troops would parachute in a few days beforehand. Alas, foul weather foiled the drop, and the Grouse quartet had to wait until the next full moon period. Making the best of things, they snagged a reindeer for Christmas dinner and feasted on fried tongue and liver soup; for dessert they had brains seasoned with blood. To make things extra jolly, they erected a stunted juniper branch for a Christmas tree and listened to carols on their makeshift radio, placing the receiver inside a pie tin to amplify the sound.
The next full moon fell on January 21. But, déjà vu, the British pilot got lost the night of the drop and spent two hours circling the rendezvous point, unable to spot it. The Gunnerside crew in the plane begged for permission to jump anyway—we can “sniff our way to the dance floor,” they assured him—but the pilot refused. And before the commandos could talk him around, sparks exploded beneath the wings. The plane was taking flak, and the pilot had to abort the drop and race back to Scotland. The British radioed an apology to the Grouse team, but it was cold comfort: they now faced another whole month on the plateau.
The Gunnerside six were no less frustrated. Rønneberg and company didn’t really grasp what heavy water was, and the phrase nuclear fission meant nothing to them. But if so many good men had already died on the Freshman mission—and if their superiors still wanted to attack Vemork, despite the increased danger—well, that told them enough.
Thankfully, everything came together during the February 17 drop. The weather was clear, and for once a British pilot found the rendezvous point. A green light flashed in the cargo hold, and the Gunnerside commandos began tossing their equipment out before anyone could change his mind. Seconds later they took the plunge themselves.
Naturally, a blizzard kicked up as soon as they landed on the plateau, an epic five-day whiteout. The six men were barely able to find a cabin to break into, and they hunkered down in their special rabbit-fur underwear to wait out the storm. At one point the winds grew so fierce that they feared the cabin would lift off the ground, Dorothy Gale–like, and go tumbling through the air. When the storm ended they poked their heads out—and immediately realized that the pilot hadn’t found the rendezvous point after all. They were supposed to land above the tree line, the elevation at which trees stop growing. But even through the snow, they could see a few gnarled trunks. Scouring maps in the cabin, they determined that they were twenty miles northeast of the meeting point with the Grouse team. Time to start walking.
But before they got going, they spotted movement in the distance—a skier. Was he a friend, a quisling, a Nazi? They had no idea. A German patrol seemed most likely, though, so they ducked back inside the cabin, hoping he would pass by. No such luck. He was coming straight for them. Which meant that even if they hid, he was bound to notice their footprints. They had no choice but confront the lone wolf.
They waited until he was just steps from the door. Then they pounced, surrounding him in seconds. He wasn’t dressed like a Nazi, but that didn’t mean anything. “What are you doing in the mountains?” Rønneberg demanded.
He turned out to be an old poacher, skiing from village to village to sell reindeer meat. He seemed harmless—until some sharp questions exposed him as a Nazi sympathizer. He then shocked the soldiers by insulting the exiled Norwegian king and his family. “They’ve never done me any good. They can just stay where they are.” Given this defiance, the poacher seemed likely to squeal, and some of the commandos voted to shoot him, arguing that he’d betray the mission. Rønneberg overruled them. The poacher knew the landscape intimately, he argued, including places to hide. Far better to make the man our guide.
It turned out to be an inspired decision. The Gunnerside crew had hundreds of pounds of equipment with them, and they faced an awful week of drudgery now, fighting headwinds at every step as they dragged their gear across the plateau. Indeed, it would have been a Sisyphean nightmare if not for the poacher. He had a real gift for finding gentle counters and skirting rough patches; Rønneberg thought his skiing “beautiful to watch.” Even with all their equipment, they were soon making good progress.
Until a crisis hit two days later. Without warning, two black dots appeared on the horizon. More skiers—probably Nazi patrols this time. Had the old man led them into a trap? Cursing him, the Gunnerside group ducked behind some cover.
The skiers slowly grew larger as they approached. They eventually mounted a nearby hillock and began scanning the terrain with binoculars. When it became clear they weren’t moving on soon, Rønneberg sent a scout down to get a read on them.
Creeping up to the hill, the scout finally got close enough to make out the two men’s faces. Or at least parts of their faces: they had heavy beards, and their skin looked oddly yellow. Disconcertingly, their movements seemed careful, guarded—they moved like soldiers, not weekend skiers on a lark.
Feeling he had to do something, the scout removed his pistol and, bracing himself, coughed to get their attention. The two men whipped around, their own guns leveled. All three stared at each
other for a second—then whooped in delight. The “Nazis” were actually members of the Grouse team, out searching for Gunnerside. They’d grown beards to keep warm, and their skin had yellowed from malnutrition.
After a joyful Grouse-Gunnerside reunion, Rønneberg decided to let the old poacher go, albeit with a threat. Rat us out, he warned, and we’ll tell the Nazis you served as our guide. That will get you executed, too. All eight soldiers then watched him ski off. He still moved beautifully, but they feared that Rønneberg’s mercy would come back to bite them.
After a few days of rest—and of feasting on raisins and chocolate for the Grouse team—the saboteurs got to work. The assault was scheduled for February 27, a Saturday. The night before, Rønneberg sent a scout to Vemork for the latest intelligence, because he still had one crucial decision to make—how to approach the plant. Vemork sat on a rock ledge overlooking a gorge, which limited their options. One possible approach was the road the workers came in on, which led to a bridge that spanned the gorge. This was the easiest approach, and taking out the two guards on the bridge seemed straightforward. But if the guards managed to sound the alarm or shout for help, the mission would be over. Killing guards would also damn the local villagers to reprisals. A second approach involved descending a set of stairs hacked into the cliff behind the rock ledge; these ran alongside the sluices that fed water into the plant. The steps were icy, however, and rigged with booby traps and mines. For these reasons Rønneberg favored a third approach, the only one that was unguarded—in part because it was unguardable. It required climbing down the sheer rock face of the six-hundred-foot gorge in front of the plant, then scaling the other side. A few commandos had dismissed this route as impossible, but reconnaissance photos showed plants growing on the rock face. And if plants can grip the walls, one of the commandos argued, so can human hands. Sure enough, the scout that night confirmed that the gorge walls were dotted with juniper bushes and shrubs. For Rønneberg that decided it—they would climb in and out. Whatever doom his comrades might have foreseen, they were good soldiers and fell in line.
