The Winter Fortress: The Epic Mission to Sabotage Hitler's Atomic Bomb

Finally, Rønneberg, the leader of Gunnerside and the last surviving saboteur, who was ninety-six years old in 2016, often spoke eloquently about why he braved the North Sea to be trained in Britain and why he then returned, twice, by parachute, to Norway. “You have to fight for your freedom,” he said. “And for peace. You have to fight for it every day, to keep it. It’s like a glass boat; it’s easy to break. It’s easy to lose.

Our home villages with the hills, mountains and forests, the lakes and ponds, rivers and streams, waterfall and fjords. The smell of new hay in summer, of birches in spring, of the sea, and the big forest, and even the biting winter cold. Everything . . . Norwegian songs and music and so much, much more. That’s our Fatherland and that’s what we have to struggle to get back.

For a brief spell, he would try to avoid all war news and think only of science and history and the pursuit of knowledge for its own sake. It would not be easy.

He held the post until the end of the war, an end that Leif Tronstad did not see for himself.

In mid-1944 Hitler, increasingly deluded and desperate, proclaimed Axis victory was imminent. “Very soon I shall use my triumphal weapons, and then the war will end gloriously . . . Then those gentlemen won’t know what hit them. This is the weapon of the future, and with it Germany’s future is likewise assured.

When you have a chest of jewels, you don’t walk around it. You plant yourself on the lid with a weapon in your hand.

He had always figured it was going to be a one-way journey, he said, and now he wanted his leader to know that he did not intend to slow down the team if they had the chance to escape. He would find his own way. “Nonsense,” Rønneberg said flatly. “You’ve kept up with us until now, and you can keep up with us to Sweden.” For this decision the young leader did not offer a vote.

What nature and time could not mend, their friendship supported them through. Until the end of their lives, Kompani Linge members gathered often to share experiences that few others could understand.

Knut Haugland spent 101 days in 1947 as the radio operator on the Kon-Tiki, a simple raft that crossed the Pacific Ocean with only a six-man crew. Beyond offering great adventure, the journey exorcised his own demons.

Laurence Binyon’s poem “For the Fallen” was read in English and in Norwegian translation at the ceremony: “They shall grow not old, as we that are left grow old: / Age shall not weary them, nor the years condemn. / At the going down of the sun and in the morning, / We will remember them.

Some, like Heisenberg, were already putting together the framework of their own defense, conveniently justifying the failure of their efforts as a calculated strategy to keep Hitler from obtaining the bomb.

At 6:00 p.m. on August 6, 1945, a short BBC bulletin reported that an atomic bomb had been dropped on Japan by the American B-29 bomber Enola Gay.

In Farm Hall, a quiet country house outside Cambridge, ten Uranium Club scientists were waiting for a decision to be made about their fate. They had been held there since July 3, 1945, rounded up when the Nazi regime fell, along with their papers, laboratory equipment, and supplies of uranium and heavy water. Among them were Otto Hahn, Werner Heisenberg, Walther Gerlach, Paul Harteck, and Kurt Diebner.

A week after the celebration, on June 28, 187 members of Kompani Linge, with Poulsson and Rønneberg in the lead, paraded in uniform before King Haakon. Of their select unit, fifty-one had died during the war. The king paid tribute to the men and their clandestine work.

The invaders numbered almost four hundred thousand, Milorg roughly forty thousand. There could have been an ugly fight, but there was none. At last Norway was free, and parties broke out in the streets of Oslo and throughout the country.

The order to mobilize was given on May 8, 1945, the day Churchill declared victory over Germany from a balcony overlooking Whitehall to a throng of revelers. The forces throughout Norway, including deep in the heart of Telemark, went into action. After years of fighting as an underground army, they put on uniforms and simple armbands and took back Rjukan and the surrounding towns.

By spring 1945, the time for action looked imminent. Nazi Germany was collapsing, and the march into Berlin would soon cut off the head of the snake. Throughout Norway, the sabotage of railway transports, ports, ships, and communication lines was hobbling the Wehrmacht and obstructing the removal of its troops to reinforce their defenses inside Germany itself.

At long last, on October 5, Tronstad returned to Norway, dropping by parachute into the Vidda. His “long exile” was over.

There was a danger that the Germans would implement a scorched-earth policy when they withdrew their 350,000 troops, as they had done when leaving Italy.

Since the Allied thrust into France just over a week before, it had become clear that there would be no invasion to free Norway. His countrymen would have to do it themselves.

By Heisenberg’s calculations, he was sure to have a self-sustaining reactor if he could only obtain 50 percent more uranium and heavy water. He would get neither.

By the end, there was only one conclusion to draw: “Germany had no atom bomb and was not likely to have one in any reasonable time.

Within days, Tronstad received final confirmation from Skinnarland’s spies that the entire shipment of Vemork’s heavy water—except for a few drums of nearly worthless concentrate—was at the bottom of Lake Tinnsjø.

Tronstad knew that if he refused to dispatch Haukelid to take care of the ferry, the Allies would bomb Vemork again before the shipment left the plant or while the train or ferry were in motion. Many more innocent civilians would die in these scenarios.

German scientists had perfected the shaped charges that could bring about these collisions at very high temperatures. Diebner and his team began putting together a series of experiments that would squeeze deuterium atoms together through the use of explosive shock waves inside a hollow silver ball, their goal being to trigger a fusion reaction—and create a bomb.

If production continued, the Allies would likely attack Vemork again. He wanted to move the plant’s high-concentration equipment—including all existing stocks of heavy water at every level of concentration—to Germany, where a new plant would be constructed.

The Allies had broken their word. Without consulting the Norwegian government, they had sent a fleet of bombers to strike Vemork. Many civilians had died. Much needless destruction had been wrought, especially on the nitrate plant in Rjukan. That site had never appeared on any target list and only produced fertilizer for Norwegian agriculture. Hardest to accept was the fact that the primary target, the heavy water plant, had not even been damaged, just as Tronstad had warned it would not be.

In the hills of Tennessee, monumental plants were being built to separate the rare isotope U-235 from U-238 using two different methods. Beside the Columbia River in Washington State, construction had commenced on reactors that used two hundred tons of uranium moderated by twelve hundred tons of graphite. Working with their Canadian ally, the Americans were building a massive heavy water plant at a hydropower station in Trail, British Columbia. At the Los Alamos Ranch School in New Mexico, a small city of physicists was working to build a functioning fission bomb.

Beside the Columbia River in Washington State, construction had commenced on reactors that used two hundred tons of uranium moderated by twelve hundred tons of graphite. Working with their Canadian ally, the Americans were building a massive heavy water plant at a hydropower station in Trail, British Columbia. At the Los Alamos Ranch School in New Mexico, a small city of physicists was working to build a functioning fission bomb.

The storm raged with renewed power. Visibility was zero. The general lassitude of all members of the party was still very much in evidence.” All the world was snow and wind, and there appeared no escape from its hold.