The Winter Fortress

by Neal Bascomb

  After this stint, they moved back to Trondheim, where Tronstad continued his research, lectured on atomic chemistry, and earned his doctorate with a well-received work about measuring the oxidized surfaces of iron and steel. More overseas study followed at the famed Cavendish Laboratory at Cambridge University in Britain, where he furthered his electrochemical work and got to know the university’s leading lights, including Ernest Rutherford.

  In summer 1932 the Tronstads returned to Norway; soon after, their daughter Sidsel was born. In his diary Tronstad wrote, “A great day today . . . Gosh, is she pretty!”

  Talented not just in the lab but also in theoretical work, Tronstad found many opportunities open to him. Since his student days, he had wondered whether he should work in industry or academia. The former paid well, and after a life spent saving every krone, that was attractive. Academia paid far less, but a professorship would provide the opportunity to teach and research pure science without being enslaved by the bottom line. In the end he told Bassa that, while he wanted to be a professor, he would leave the decision to her. “If you like, I can make as much money as you want,” he said. She gave him her blessing to return to the university. He was soon a full professor at NTH, published scores of research papers, and dazzled his students by igniting chemical compounds at the touch of a feather. He bought a nice house a short walk from the university and a car to drive out to his mountain cabin, where the family could ski and hike. He taught his daughter to ice-skate, and in August 1937 he welcomed a son, Leif Jr., who liked to be pushed around the yard in a wheelbarrow.

  During these prewar years, Tronstad also worked as a consultant to several Norwegian companies. He advised them on the manufacture of steel, rubber, nitrogen, and aluminum, and, for Norsk Hydro, heavy water.

  On November 11, 1940, seven months after the Germans invaded, Tronstad visited Vemork at the request of Jomar Brun. Tronstad’s former classmate, narrow of frame, with round spectacles that matched his softly featured oval face, had said he’d wanted help in making improvements at the hydrogen plant. In truth Brun was also looking for insight into why the Germans were so interested in heavy water, and what he should do about it.

  Shortly after Rjukan was taken, a German general visiting Vemork had ordered production at the plant—and deliveries to Berlin—increased at a rapid rate. He’d revealed nothing about the intended use of the heavy water. Brun had already implemented the expansion of high-concentration cells from seven to nine. This upgrade, as well as the laundry list of improvements suggested by Tronstad over the course of his two-day tour, including adding nickel-plated anodes to the cells to prevent rusting and increasing their amperage, would enable the plant to supply the Germans with 1.5 kilograms a day of heavy water, an increase of five times its former production level.

  In private, after their work at the plant was finished, Tronstad and Brun wrangled with the question of why the Germans needed so much heavy water. As an avid reader of science journals, Tronstad knew there was interest in the substance as a moderator in the new field of fission research. Further, he had collaborated with Ernest Rutherford in 1935 in an attempt to produce tritium (an even rarer isotope of hydrogen) at Vemork. They failed, yet Tronstad understood well Rutherford’s theory that tritium and deuterium could be used to obtain a fusion reaction with a potentially enormous energy release. Nonetheless, Tronstad dismissed the idea that heavy water could be applied to any great military use. Instead, he and Brun conjectured that the Germans might want deuterium for some kind of poison gas, but they doubted this application would yield results. Whatever the reason, Tronstad decided, if the Nazis were interested in heavy water, then so too should he be.

  As for Brun, they agreed that he should remain at the plant and do whatever was necessary to keep his job, including making changes that would raise production levels. This was the only way he could stay informed of new developments. Anything significant, and he should alert Tronstad.

  After his visit to Rjukan, Tronstad returned to Trondheim, where he had resumed his teaching and studies at NTH. He channeled most of his prodigious energy, however, into his activities with the underground resistance, working particularly closely with several bands of university students who were pushing back against the German hold on the country. Some published illegal newspapers. Others operated at a higher level, connecting with the British Secret Intelligence Service (SIS), the foreign intelligence agency. Under the moniker Skylark B, these students sent coded wireless-radio transmissions from the forests outside the city to London, reporting on troop movements and naval activity.

  Codenamed the Mailman, Tronstad gave them any technical help they needed and provided intelligence of his own. With his industrial connections, he gathered information on Norwegian firms and how they were helping the Germans. Norsk Hydro was but one focus of many. The resistance was a precarious web that he feared might be unraveled at any time, yet he continued spinning new threads within it.

  In March 1941 Brun reported that German officials, accompanied by scientists, had once again descended on Vemork. They now wanted a nine-stage cascade before the high-concentration stage—thousands more electrolyzer cells. They demanded fifteen hundred kilograms of heavy water a year, and they were making Brun “personally responsible for a perfect running of the plant.” Soon after, Alf Løken, a chemistry student and member of Skylark B, approached Tronstad. SIS wanted them to provide everything they had on Vemork’s heavy water. Tronstad told Løken all he knew. This was sent by wireless to London.

  The Tronstad family spent several weeks that summer in their mountain cabin. Since the occupation, Tronstad had tried to keep things as normal as possible for his wife and children. But he was nervous. The Gestapo had tracked down Skylark B’s wireless transmitter outside Trondheim and had tortured a student who was involved in its use. His confession led to several other arrests, including that of Løken. Others in Skylark B fled. Around this time, Brun came to the city with urgent news. The Germans now wanted to increase heavy water production to five thousand kilograms a year, and Paul Harteck, whom Tronstad knew from Cambridge, was on his way to advise on new methods to obtain such levels. Realizing the importance of conveying this information to the British, but with Skylark B in jeopardy, Tronstad found a courier—a man planning to escape by boat to Scotland the following week. He gave him precise details on Vemork, including its monthly production figures. The courier wrote these details down on some cigarette paper.

  The Gestapo was close to breaking up Trondheim’s resistance. On the morning of September 9, a student visited Tronstad for advice on securing Skylark’s radio equipment. The student was arrested that same afternoon. A week later, Tronstad’s courier was seized at the wharf’s edge. Fortunately he was able to swallow the cigarette paper before being hauled away. On September 20, one of the arrested Skylark members, fearing he might break under torture, managed to pass on a message to a friend through the barred windows of the Gestapo prison: “The Mailman must disappear.”

  Tronstad warned Bassa that they might need to flee, and two days later, when informed of yet another arrest, he went straight to her. It was their thirteenth wedding anniversary. “We must go,” he said. They made their way to the train station with some hastily packed suitcases; there was a 7:15 p.m. train to Oslo. Bassa and the children boarded first. Tronstad looked left and right, fearing the Gestapo might be waiting for him on the platform. Once safe on the train, he settled down in the sleeping compartment with his family and wrote the first entry into the small, black diary he would keep throughout the war. “Family, house and worldly goods have to be set aside for Norway’s sake.”

  At 10:15 a.m. they arrived in Oslo and took another train to Sandvika. They climbed up the hill, past the small kiosk where Tronstad’s mother used to work. Farther up, they reached Bassa’s childhood home. He instructed Bassa to tell anyone who asked that he was in Rjukan. Then they embraced. “I’m not afraid of anything,” he told Bassa. “That is exactly what I’m afraid
of,” she responded.

  Outside the house overlooking the fjord, he kneeled beside his children. “Take care of your little brother,” he told nine-year-old Sidsel. Then he turned to four-year-old Leif: “You must be good for your mother while I’m gone.” He promised to bring back a little gift for each of them. Sidsel asked for a watch; Leif, a motorized go-cart. “Be kind to each other,” Tronstad said before hurrying away, overcome with emotion. He was on his way down the hill when he heard young Leif call out, “Where are you going?”

  Tronstad swung around. “Notodden.”

  “You’d better hurry up.” Leif pointed to the train moving into the Sandvika station below. Tronstad started to run down the hill, but the truth was he was not catching that train. Rather, he would wait on the platform to catch one heading in the opposite direction.

  In Oslo he collected fake identity papers, and the next morning he borrowed a bicycle and rode twenty miles north to Sandungen, where his brother-in-law worked as a forester. For a day, Tronstad marked trees for felling and wondered if he should just wait out the war as a “hermit” in the forest. But he dismissed the thought. That night, he wrote a letter to Bassa. Falsely dated the night they’d left Trondheim, the letter spoke of his inability to remain at a university where those allied with the Germans received “preferential treatment,” while he was slandered. The letter continued: he was now in Sweden, but he had not done, nor would he do, anything “dishonest or illegal.” The letter was meant to provide Bassa with cover in the event she was interrogated by the Gestapo.

  The next morning, September 26, two members of the resistance network picked him up in a truck. They drove toward neutral Sweden, a hundred miles away. An hour’s hike from the border, they got out and set off on foot through the woods. They crossed into Sweden at 5:00 p.m., and a couple of hours later Tronstad was arrested at a Swedish military post that had an understanding with the network. They gave him a steak, beer, and some coffee.

  A month passed before Tronstad gained passage to Britain, from where he hoped to continue his fight to free Norway. His passport, stamped in Stockholm, was “Good for a single journey.” Aboard a bomber converted to a transport plane, he crossed the North Sea at high altitude, breathing through an oxygen mask. After seven hours in darkness, the plane, having fought headwinds the whole way, finally landed in Scotland.

  On October 21, Tronstad arrived at King’s Cross station in London. As arranged by SIS, a room was booked for him at the St. Ermin’s Hotel in the heart of Westminster, a stone’s throw from the spy agency headquarters. London, a city he knew well from his student days, was a war zone. Soldiers crowded the streets, and a floating armada of gray barrage balloons darkened the sky, defending against German bombers.

  In Stockholm, Tronstad had read about the Blitz in the newspapers. Since September 7 the previous year, Hitler had sent his planes into the heart of London to break its fighting spirit. Incendiaries sent fires sweeping across rooftops. Explosives ripped apart houses and buildings. Many thousands of people had been killed in the attacks and countless more wounded or left homeless. But it was one thing to read about the devastation and another to see it. Although the attacks had largely relented by May 1941, the streets were still strewn with the rubble of bombed-out buildings, and the people he passed had a joyless, though determined, mien.

  When Tronstad finally went to bed, British fighter planes patrolling the skies thundered overhead. Such was his exhaustion from the journey that he slept easily through the din.

  St. Ermin’s, a horseshoe-shaped Victorian hotel, was the perfect location for clandestine meetings, with its grand, busy foyer and many nooks and crannies. On his first Sunday in London, Tronstad sat down across from Commander Eric Welsh, head of the Norwegian branch of SIS. Welsh ran Skylark B and had choreographed Tronstad’s journey to London.

  The spy was short and overweight, with a huge dome-shaped head. Slovenly dressed, he chain-smoked; cigarette ash dusted the front of his shirt. He may not have looked like a hero, but in the previous world war, Welsh had won medals for gallantry as a minesweeper. He became an officer in Naval Intelligence, focusing on scientists and their work, before being transferred to SIS. His wife was Norwegian, a relative of the composer Edvard Grieg, and his knowledge of the language earned him a position with a Norwegian paint company that serviced a lot of the country’s industrial firms. In fact, Tronstad soon learned, Welsh knew Jomar Brun and Vemork quite well. He had sold the corrosion-proof tiles for the flooring in the high-concentration plant.

  Welsh knew many things, a lot of them from an informant inside Germany codenamed the Griffin. This was the scientist Paul Rosbaud, who, as an adviser for the scientific publisher Springer Verlag, was close to Hahn, Heisenberg, and other leading German physicists. He provided early reports of the Nazi atomic program, but since Army Ordnance had taken over, the intelligence had slowed. Welsh also had the inside track on Britain’s development of an atomic bomb, under what was known first as the MAUD (Military Application of Uranium Detonation) Committee, then as the Directorate of Tube Alloys.

  Welsh spoke in a ramble and garbled his words, which made the little of import he shared with Tronstad almost unintelligible. Regardless, Welsh was not there to reveal his own secrets but to learn what his new arrival had to offer. Tronstad was open from the start. Vemork was now producing four kilograms of heavy water a day for the Germans—with more to come. The two spent the whole morning together, not all of it in discussion about heavy water. Tronstad knew from other sources that the Germans had secured uranium oxide from Norway, and there were also his contacts with former students and colleagues in Oslo, Berlin, Cambridge, and Stockholm, which might bring in more intelligence. Welsh expressed his hope that Tronstad would lend his own expertise to aid the war effort. No firm next steps were set, but Tronstad made it clear that he was eager to be of help.

  And indeed, Tronstad’s involvement in the resistance continued to grow. One day he met with a Skylark member who had escaped to London. Another day, he was at the Thatched House Club, a gentleman’s club and den for members of the British secret services. He ate a dinner of oysters and pigeon with those tasked with commando operations in Norway. The next day he spent at Norway House, off Trafalgar Square, the center for the exiled community, where he was introduced to top government officials—“celebrities,” he wrote dismissively in his diary. Next he met with leaders of Milorg, the umbrella organization of military cells of which he had been a part in Trondheim. They were pushing to be officially incorporated into the Norwegian Ministry of Defense. Then he had an appointment with the E-Office, Norwegian intelligence, then one with the defense minister, then an audience with the crown prince. Throughout, Tronstad looked for a way to be of most use to his country.

  Time and again over his first six weeks in London, Tronstad was called into conferences with the British scientific community associated with Tube Alloys, all brought about through Welsh, who let it be known that Tronstad was a man “acquainted with the particular subject which I think interests you.” Tronstad knew some of the scientists from his Cambridge days, but others were new connections. He was introduced to Harold Urey, who had discovered deuterium and who was on a fact-finding mission in London for the United States’ own program. Any doubt that remained for Tronstad about the German need for heavy water was dispelled. It was to be used in atomic research, potentially for a bomb. The only unknown was where the Germans stood in the race to build it first.

  During these weeks, Tronstad participated in several strategy sessions on how to stop the supply at Vemork. Wallace Akers, a chemist well known to Tronstad and now head of Tube Alloys, brought him in to discuss a British Air Ministry plan to bomb the plant. Another plan, codenamed Clairvoyant, targeted six hydroelectric plants in southern Norway, Vemork included, with six teams of saboteurs operating in tandem. Tronstad argued against both. The plant was a poor target for nighttime bombers, and Clairvoyant was too ambitious. Instead, he suggested a targeted operation by No
rwegian agents or sabotage from the inside.

  Tronstad was unsure how, or if, his advice was taken—he was very much the outsider—but it seemed that little came from these sessions and that the urgency from the British side to do something about Vemork waned. By the end of December, after participating in a six-week Norwegian Army training course in Scotland, he was still looking for his place in the struggle to liberate his country. Many wanted him to focus on scientific work for the war effort, but he wanted to return to the action. As he wrote late one evening, “I want to be close to those fighting on the frontlines for Norway’s cause.”

  3

  Bonzo

  * * *

  BEFORE DAWN ON December 2, 1941, Knut Haukelid was roused by dogs barking outside his room. There was a chill in the air, and frost clouded the windows overlooking the huge wooded estate of Stodham Park, fifty miles southwest of London. Quickly, Haukelid dressed in his new British uniform, its starched collar surpassed in stiffness only by his standard-issue boots.

  Outside, he stood with roughly two dozen other Norwegians who had volunteered to attend special commando training to fight for their country. They came from every walk of life—rich, poor, and in between; from city, town, and backwoods country. A few had never handled a gun before; others were marksmen. Some were boys, barely eighteen. Most were in their twenties, and a few were old men—all of thirty, like Haukelid. Before the war, they had been students, fishermen, police officers, bankers, factory workers, and lost types, looking for their place in the world—again, like Haukelid.

  At first glance, he looked like many of the others. Although his twin sister, Sigrid, was a Hollywood movie star, known as the “siren of the fjords,” there was nothing particularly handsome about him. He had fair hair, blue eyes, and a medium build, with slightly hunched shoulders. At five ten, he was just above average height. But there was something in his look, in the way his face went from the crinkle of a smile to hard intensity in an instant, that was unforgettable.