The Winter Fortress Read online

  Once they had enough uranium and an effective moderator, Heisenberg concluded, it was simply a question of calculating the machine’s most efficient size (quantity of uranium and moderator), arrangement (mixed together or layered), and shape (cylindrical or spherical). His initial figures indicated that a sphere filled with at least a ton each of uranium and the chosen moderator separated in layers would be optimal. It was going to be big, but it would work.

  Heisenberg gave Diebner the direction he needed to move forward—and the Nobel laureate’s reputation contributed to persuading others to follow this path. Experiments would continue to separate U-235, but most of the effort was now focused on building the uranium machine. If they were successful, they would prove at last the importance—and utility—of atomic physics. Constructing a bomb would follow.

  In recognition of the Uranium Club’s work, Diebner was named head of the Kaiser Wilhelm Institute of Physics in Berlin, a body of preeminent reputation and the country’s most advanced laboratory. Heisenberg was appointed to the board as scientific adviser, to placate those who were upset at having Diebner, a physicist of no renown, directing the august institute.

  By year’s end Diebner had dozens of scientists under his watch across Germany refining the uranium-machine theory and building the first small experimental designs. Progress had been made outfitting laboratories and ordering uranium oxide and other key materials.

  Although the issue needed further study, the scientists’ calculations indicated that heavy water was the best presently known moderator. The Uranium Club would require a steady, robust supply of the precious liquid. Unfortunately, the world’s sole producer, Norsk Hydro’s Vemork plant, was far away in an inaccessible valley in Norway, a country whose neutral status in the war made it an unreliable partner. The plant had also only recently restarted heavy water production in November 1939 and could supply little more than ten kilograms a month. Diebner considered building a full-scale heavy water plant in Germany, though it would cost tens of millions of marks and consume a hundred thousand tons of coal for each single ton of heavy water. Before he made any such move, however, he and Heisenberg agreed that they needed to make sure heavy water was a viable moderator. For those experiments, twenty-five kilograms should do. Diebner had a representative of the German conglomerate IG Farben, which owned 25 percent of Norsk Hydro, put in the order, to conceal the involvement of Army Ordnance.

  By January 1940, with more physicists in his group asking for their own supply, prospective orders had grown to one hundred kilograms a month, every month. Norsk Hydro wanted to know the purpose of such a large order, but with experiments using heavy water now labeled SH-200, a high-level military secret, the IG Farben representative offered only silence.

  Not long after, the Norwegians did find out, from Jacques Allier, what that purpose was: the potential development of an atomic bomb.

  When Allier visited Vemork on March 5, 1940, he presented himself merely as an official with Banque de Paris. Axel Aubert led the meeting with the plant’s lead engineer, Jomar Brun. From previously unsold supplies and the restart of production, the plant had a total of 185 kilograms at hand. All of it, Aubert told Brun, needed to be transported secretly to Oslo by truck. Brun asked to know why, just as he had asked why when Aubert had quietly told him earlier in the year to explore a fivefold increase in production to 50 kilograms a month. As before, Aubert declined to answer any questions and instructed that not a word of this special order was to be mentioned to anyone.

  After settling these arrangements and finding a Rjukan welder to make twenty-six stainless-steel flasks that would fit neatly into suitcases, Allier returned to Oslo with Aubert to conclude their negotiations and prepare for spiriting the flasks out of Norway. The Norsk Hydro director general offered to give France the heavy water on loan, with no price attached, and told Allier that Norsk Hydro would provide France with first claim on what was produced in the future. Impressed by this generosity—and the alacrity with which Aubert had moved—Allier opened up about the intended use of the heavy water by Frédéric Joliot-Curie and his team.

  On March 9, two trucks departed Vemork down the steep, ice-slick road. Brun rode in the first truck. At a nondescript house in Oslo, they unloaded the twenty-six flasks and entrusted them to Allier’s care. The house was owned by the French government and was a stone’s throw from an Abwehr safe house, but sometimes it was best to hide in plain sight.

  To smuggle out the supply, Allier had grand visions of a submarine sneaking into Oslofjord and spiriting it away, but instead he settled for the old “bait and switch,” supported by the three French spies he had recruited in Stockholm. Through several ticket agents and under various assumed names, they booked flights on two planes leaving Oslo’s Fornebu airport at roughly the same time on the morning of March 12. One was headed to Amsterdam, the other to Perth, in Scotland. In case anything went wrong, they also bought seats on the same flights for two consecutive days after that.

  At dawn on March 12, a frigid and cloudless morning, Allier and a fellow spy, Fernand Mosse, took a taxi three miles south of the city center to Fornebu. Dressed as businessmen, they made a big show of their upcoming trip to Amsterdam in front of the gate agents and baggage handlers who took their several large, heavy suitcases. Soon enough, they were crossing the tarmac toward the Junkers Ju-52 aircraft designated for their flight. Adjacent to their plane was an identical one, destined for Perth.

  Once they were sure their baggage was loaded onto the Amsterdam-bound plane and its propellers began to spin, they readied to board. At that moment, a taxi drove onto the tarmac. Its passenger, Jehan Knall-Demars, another of Allier’s team, had pleaded with the gate agent to let him through in the taxi so he could make his plane to Amsterdam. The spy had the taxi park between the two Junkers, out of view of the Fornebu terminal. From the trunk, he unloaded several suitcases, together containing thirteen of the heavy-water flasks. These were hauled into the baggage hold of the Scottish-bound plane, which Allier and Mosse boarded, instead of the one to Amsterdam. Knall-Demars left in the taxi, hiding in the back as he passed through the gate.

  Minutes later, the plane to Amsterdam barreled down the runway and lifted into the sky. As it headed south over the Skagerrak, the strait of sea between Norway and Denmark, a pair of Luftwaffe fighters drew alongside. They ordered its pilots to divert their course to Hamburg. When the plane landed in Germany, Abwehr agents busted open the cargo hold. Rummaging through the suitcases, they found a few that were particularly heavy. Inside them? Granite rubble.

  Meanwhile, Allier and Mosse landed safely in Scotland with their stash. The following day, Knall-Demars arrived with the other thirteen flasks.

  By March 18, all twenty-six flasks were stored in the old stone-arched cellars of the Collège de France in Paris. The first battle of heavy water was won. The next, however, was all too shortly to begin.

  2

  The Professor

  * * *

  TO TRONDHEIM they came, in the dark, early hours of April 9, 1940, cutting into the Norwegian fjord at twenty-five knots. A northerly, snow-flecked gale swept across the steel decks of the German cruiser Admiral Hipper and the four destroyers at its stern. They approached the three forts guarding the entrance to the former Viking capital, all crews at action stations.

  A Norwegian patrol signaled the intruding ships to identify themselves. In English, the Admiral Hipper’s captain returned that they were the HMS Revenge, there with orders from the British government to “proceed toward Trondheim. No unfriendly intentions.” As the patrol shined a spotlight across the water, it was blinded by searchlights from the Admiral Hipper, which suddenly accelerated to maximum speed, blowing smoke to obscure its whereabouts. Signals and warning rockets lit up the night. Inside the Norwegian forts, alarms rang and orders were given to fire when ready on the invading ships.

  Fifteen minutes passed. Within the port’s batteries, the ammunition had to be loaded, then the electrical firing mechani
sms failed. By the time the inexperienced Norwegian soldiers were prepared to respond, the Admiral Hipper was already steaming past the first fort. At the second fort, the bugler who should have sounded the alarm had fallen asleep at his post, and the men were late to their guns. The moment they opened fire, their searchlights malfunctioned and they could not see their targets.

  At 4:25 a.m. the small armada set anchor in Trondheim’s harbor. Cutters began ferrying two infantry companies from the warships to the shore. All was sleepy in town as German soldiers spread out from the port into the defenseless streets. The Nazi invasion of Norway had begun.

  In an auditorium at the Norwegian Institute of Technology (NTH), a twenty-minute walk from Trondheim’s harbor, students, teachers, and a handful of other community members had gathered. Word of the invasion had reached Leif Tronstad before the break of day, and while his children slept he had rushed to the institute. From the scarce reports he and the others had received, all of Norway looked to be under attack. Bergen, Stavanger, Kristiansand, and Narvik had fallen alongside Trondheim, but Oslo was rumored to be holding out. The panicked assembly debated what they should do. One among them, a firebrand named Knut Haukelid who was visiting friends in the city, wanted to fight with whatever weapons they could find. Others preached caution; their small country, with its limited military, stood little chance against German might.

  When Tronstad spoke, he held everyone’s attention. At thirty-seven, he was the university’s youngest full professor, and a favorite in its classrooms. Of medium height, he had blue eyes, a hatchet-sharp nose, and ash-blond hair parted neatly on the side.

  Tronstad informed those assembled that, as a reserve officer in the Army Ordnance Corps, he had standing orders to travel to Oslo if war broke out. He advised those with military experience to do the same. As for the others, he said, each man needed to follow his own conscience on what action to take, but he reminded them that their country needed them. With that, he said his goodbyes.

  Tronstad had feared this would happen—that Norway’s “sleeping government” would leave the country unprepared to mount a defense in the event of an invasion. Since the day Hitler invaded Poland seven months earlier, it was plain to Tronstad that Norway would not be allowed to maintain the neutral stand it had held during the Great War. The fight between the Allies and the Nazis in mainland Europe had stalled, and the two sides had circled Norway for months, waiting to see which would make the first move toward bringing it within their sphere of influence.

  There were good reasons for their interest, chiefly because Norway’s long coastline offered potential naval bases to dominate the North Sea. All the while, the Norwegian government hoped measured diplomacy would trump the need for force. Only a few days before, the German ambassador, Curt Bräuer, had thrown a party for over two hundred Norwegian political and military guests. Midway through, the lights were dimmed and a film, Baptism of Fire, was screened. To a soundtrack of Richard Wagner, bombers obliterated Warsaw while a voiceover explained that this was the consequence for those who made friends with the British and French. The film concluded with a map of Britain bursting into flames and the flash of a Nazi swastika.

  Hurrying home, Tronstad found the city around him quickly occupied by German soldiers. They marched in columns through the streets. They established machine-gun nests and mortar positions on bridges and key spots throughout the city, and called out warnings in German to not resist. Tronstad ignored them. Finally, he reached his two-story house on the leafy outskirts of the city center. He told his wife, Bassa, that they were not safe in Trondheim. He would take her and the children to a tourist mountain lodge at Kongsvoll, a hundred miles to the south, then he would travel on to Oslo to join the army.

  Together they woke up their daughter, Sidsel, age seven, and two-year-old son, Leif Jr., and helped them dress and pack. Fifteen minutes later they piled into their Opel Super 6, a luxury German-made car. As they headed south over the Nidelva River bridge, two ash-colored bombers flew overhead.

  “What kind of plane is that?” Sidsel asked.

  “It is a German plane,” Tronstad said, his first explanation of their hurried departure. “I’m afraid the war’s come to our country.”

  They reached Oppdal, a small town and the end of the road in wintertime, that afternoon. The news they heard there was not good. The call to mobilize had finally come through, but the “iron ring” of defense around Oslo had proven to be a fiction: the Germans controlled the capital. King Haakon VII, a tall, austere man who rose to the throne in 1905, had fled the city, as had the Norwegian government. On the radio, Vidkun Quisling, the head of the fascist Nasjonal Samling Party, announced that he had assumed governmental powers. Tronstad knew now that it was no use, his traveling to the capital. He took his family to the Kongsvoll lodge and left the next morning to join the local army command.

  The day after the invasion, the sleeping Norwegian government finally roared awake. Bräuer stated his demands to King Haakon. The king brought these to Prime Minister Johan Nygaardsvold and his ministers, informing them that personally he could accept neither Quisling nor surrender but that as he was a constitutional monarch, it was not in his power to decide. If the government chose to make peace with the invaders, however, he would immediately abdicate. The government sided with their king, who then broadcast a message to his people over the radio: they should struggle and fight until the invaders were thrown from Norway’s shores.

  Pockets of resistance formed throughout the country, but backed by British and French reinforcements, the Norwegians put the greatest effort into two places: the naval stronghold Narvik and two long valleys between Oslo and Trondheim. If the Germans controlled that region, which separated the north–south corridor from the capital, then they would hold the heart of Norway.

  It was here, with German panzer battalions backed by the Luftwaffe pushing north from Oslo, that Tronstad fought his war. He was charged with preventing German troops from crossing the defensive Norwegian line. Headquartered in the Kongsvoll lodge, he created a network of men to report on enemy activity and saw to the plowing of yard-high furrows in the snow on the surrounding lakes to prevent German transport planes from landing.

  Over three weeks, aided mostly by the British, the unpracticed and outgunned Norwegians fought ferociously in the two valleys, but they were steadily pushed back toward Trondheim. Believing the battle over, the British began evacuating at the end of April. On May 1, when the surrender order came through to his district, Tronstad and several others hid eighty-one boxes of ammunition in the mountains in the hope of a future fight. That afternoon, while Tronstad was away from his family, a German cavalry unit navigating the hilly terrain reached the Kongsvoll lodge.

  In the pouring rain, the men, covered in mud and grime, marched up to the front steps of the residence. The commanding officer ordered Bassa Tronstad to clear the barn for his men and their horses. “We have cows there,” she returned in fluent German. “If we take them out, we won’t have any milk.” The officer, surprised at the rebuff in his native language, said that his men would then sleep in the lodge.

  “As long as they’re clean,” she replied.

  Before the unit left, the commanding officer stood before Bassa and threatened, “If anything happens around here, you will be shot immediately.”

  When Tronstad came back to the lodge, he collected his family and returned to Trondheim. The battle still raged in Narvik, but that too was soon over, and King Haakon and the government fled to Britain by ship. The Germans now ruled Norway. Their presence was a violation of everything Tronstad held dear, and their occupation robbed him of the life he had built from nothing.

  Three months before Leif Tronstad was born, his father, Hans Larsen, died of a heart attack. His mother, Josefine, supported her four sons by running a small kiosk and by serving as a maid at private dinner parties hosted by the wealthier families in their neighborhood outside Oslo. Growing up, Leif was either studying, at the running track,
or working. After secondary school and a couple of years employed at an electricity company, he headed to Kristiania Technical School to study chemistry. From the list of national records he set, it’s clear that he majored in athletics as well. Even with a factory job and his participation in sports, he graduated with the highest marks on record. In 1924, after fulfilling his military service and shoring up his finances, he enrolled at NTH.

  In Trondheim, he was finally able to focus on science alone, and he excelled to an even greater degree. He spent most of his waking hours poring over his books. “I work as a slave these days,” he wrote to his mother in his first year. “No need to send money. I live modestly, Spartan, and careful. Only bread and the cheapest kind of butter.” He graduated with top honors, which earned him recognition from King Haakon himself. Leif Tronstad, who had taken his mother’s maiden name out of respect for her years of sacrifice, was now a rising star.

  All this time, he had courted his childhood sweetheart, Edla, whose nickname since the time she was a toddler was Bassa. She was a few years his junior; they had grown up on the same hill in Sandvika, a neighborhood overlooking the Oslofjord, several miles west of Norway’s capital city. While away studying, he sent love letters to his “little angel” and “beautiful treasure.” One day, he promised, “we will have each other forever and be the happiest people under the sun.” At Christmas, unable “to wait until we get old with love,” he asked her to marry him.

  Following their wedding in 1928, the newlyweds moved to Berlin, where, as part of Tronstad’s three-year doctoral grant from NTH, he worked as a researcher at the Kaiser Wilhelm Institute of Chemistry. Keen with languages, Bassa worked as his secretary and translator. Together, they got their first taste of Nazism. Emblazoned across the city were posters with close-up photographs of Hitler and headlines calling to avenge the Treaty of Versailles.