Ancestral Chronicles

Sinking Hitler’s Bomb

One winter night during World War II, three men ambled onto a Norwegian ferry, bundled up against the cold. They looked like ordinary passengers, but their overcoats didn’t cover bulky sweaters. Instead, Rolf Sorlie, Knut Haukelid, and Knut Lier-Hansen concealed alarm clocks, batteries, wires, fuses, detonators, and a twelve-foot-long, nineteen-pound “sausage” of plastic explosives.

They slipped into the ferry’s cargo hold and taped the explosives against the ship’s hull, then taped the clocks and batteries to dry girders and connected the detonators to the fuses. The alarms were set to ring at 10:45 a.m. the next morning, 20 February 1944. If everything went like clockwork, the German atomic bomb program would be sunk in less than a day.

The Allies suspected that Germany had been trying to build an atomic bomb since 1938, when German scientists split the uranium atom. Suspicion turned to panic when Nazi dictator Adolf Hitler seized Norsk Hydro, a complex of hydroelectric and electrochemical plants in Vemork, Norway, early in 1940. Norsk Hydro made almost all of the world’s deuterium oxide, or heavy water, as a by-product of fertilizer manufacturing. But heavy water soon was in great demand—for research in nuclear power.

The Allies knew they had to act fast. If Hitler had an atomic bomb, he would surely win the war. So the Allies launched a top-secret mission to destroy Hitler’s heavy water—and with it his hopes of an atomic bomb.

A combined Norwegian and British effort planned to sabotage Norsk Hydro, but the plant was virtually impregnable. Norsk Hydro perched like a fortress on the side of 3,000-foot-high Barren Mountain and overlooked a sheer drop to the Maana River flowing 500 feet below. The Har-danger plateau, a frozen, 3,500-square-mile wasteland, loomed just to the northwest. But the Allies finally mapped out a plan of attack.

On 18 October 1942, a four-man advance team dubbed the Swallows plunged out of the belly of a British bomber. The Swallows were Norwegian resistance fighters Jens Anton Poulsson, Knut Haugland, Claus Helberg, and Arne Kjelstrup, and parachuting onto the Hardanger was just the beginning of their ordeal.

The Swallows landed in snow up to their waists. The twelve supply coffins stuffed with their food, clothing, and weapons had disappeared. And somehow the Swallows had touched down miles from their target. They were lost on the Hardanger.

They survived on chocolate bars and snow for days before finally tracking down their supplies. But the snow was so deep and the wind so fierce that the Swallows had to split their loads. Each man hiked a few miles with half a load, left it in the snow, and then went back and picked up the rest of the load—making their trip three times longer than estimated.

Three weeks later, the exhausted Swallows made camp high above Norsk Hydro. They signaled London: “Happy landing in spite of boulders everywhere.”

British intelligence was excited but suspicious. The message was weeks overdue. Was it really from the Swallows, or was it a trick by Germans who had captured the transmitter? British intelligence flashed a message back: “What did you see walking down the Strand in the early hours of January 1, 1941?”

There was a long pause, then the reply: “Three pink elephants.” It was the correct answer to the riddle. Now the Swallows waited for the next phase of their mission.

On 19 November 1942, thirty-four specially trained British commandos climbed into two plywood gliders at Wick Airfield in Scotland. Each glider was attached to a bomber that would tow it to the Hardanger, where the silent craft and its crew would meet the Swallows. The combined teams were to storm Norsk Hydro.

But things went wrong from the start. Soon after takeoff, telephone links between the bombers and their gliders failed. Poor weather conditions prevailed as the first pair of planes approached the Norwegian coast at 10,000 feet. The bomber pilot tried desperately to pinpoint the drop zone, but a blank canvas of snow and clouds stretched before him. With fuel running out, the bomber pilot headed for home. Just as they were crossing the Norwegian coast, the towrope snapped. The glider plummeted out of sight under the heavy clouds and crashed into a mountaintop.

The second bomber made a low approach, hoping to fly underneath the clouds and spot the release point. But ten miles inland, the weather was no better. This glider, too, smashed into a mountainside. Seconds later the bomber crashed into another mountain. German troops found the crash sites the next morning. They rounded up all the survivors and conducted a brief interrogation before executing the British fliers.

The mission was a disaster. The Allies had lost an elite group of commandos without making a dent in Norsk Hydro. And they had tipped their hand; now the Germans knew that Norsk Hydro was a prime target.

Within days the Nazis surrounded the plant with a minefield, booby traps, and antiaircraft guns. But the Allies couldn’t give up. The threat of a nuclear bomb in Hitler’s hands was too great. A new mission had to be launched immediately. This time, there could be no mistakes.

Six Norwegian commandos—Knut Haukelid, Fredrik Kayser, Hans Storhaug, Kaspar Idland, Birger Stromsheim, and Joachim Ronneberg—trained for the next assault. They memorized blueprints and information on Norsk Hydro that technician Einar Skinnarland and Norsk Hydro’s chief engineer, Jomar Brun, had sent from Norway, smuggled in toothpaste tubes. In Britain the team built an exact wooden replica of the heavy-water machinery and practiced laying explosives and making detonators inside the model.

The team parachuted into Norway on 17 February 1943. The Swallows, who had battled extreme cold and starvation since the previous October, met them on the Hardanger. The combined groups planned a complicated approach to Norsk Hydro in order to escape detection. They stashed their skis and extra equipment in a snow-bank at the top of the gorge overlooking the Maana River. Loaded with pistols, grenades, knives, ammunition, and explosives, they trekked down the steep slope and crossed an ice bridge over the swollen river before facing their biggest obstacle—a sheer wall of rock stretching 500 feet straight into the sky.

One treacherous route up the cliff was unguarded, but the team spotted a few straggly trees clinging to the rockface. And they hoped that where trees grew, men could climb.

Clawing up the cliff inch by inch, searching for finger and toeholds, they reached the top by midnight. Kjelstrup silently snipped a hole in the chain-link fence surrounding the plant. They were in.

The men split into two groups: one to sabotage the plant, the other to act as backup. Crawling on their hands and knees, the first group found a slimy cable tunnel. Leif Tronstad, who helped design and supervise the construction of Norsk Hydro, had told them that this duct was the only unlocked entrance. The commandos slithered through the narrow passageway, which took them straight into the heart of the plant.

Following their memorized blueprints, they quickly found the door to the heavy-water room. It was unlocked. Kayser subdued the watchman, a fellow countryman, and removed him from harm’s way while Ronneberg and Stromsheim set the explosives, lit the fuses, and raced back through the tunnel toward the fence. Thirty seconds later, they heard precisely what they wanted to hear: a whistling sound followed by a muffled blast.

Inside the plant, workers and guards ran to the scene. The heavy-water room looked like a huge shower stall. All eighteen cells of heavy water were destroyed. Half a ton of precious deuterium oxide had gone down the drain.

Within hours, German soldiers were combing the Hardanger, but the saboteurs escaped without a scratch. The assault on Norsk Hydro seemed like the perfect mission.

But by June, Norwegian resistance fighters reported that Norsk Hydro was back in business. The Germans had worked around the clock to repair the plant. The Allies decided to attack Norsk Hydro a third time, and this time, the attack would come from the air.

On 16 November 1943, 460 aircraft, loaded to capacity with bombs and extra fuel, took off from southern England. To divert the enemy’s attention, two divisions headed for other targets in Norway. That left the going clear for the third division to focus on the real target: Norsk Hydro.

Over 700 bombs fell toward the plant in less than thirty minutes. All but two missed. And those two bombs caused only minor damage.

But the air raid wasn’t entirely unsuccessful. Germany realized that the plant would only be attacked again, so Hitler decided to dismantle Norsk Hydro and move it to Germany for safekeeping. The heavy water would be sent by railroad to the edge of Lake Tinn, a short distance away. Then it would cross the lake on the ferry Hydro and continue by rail to the Norwegian coast to be shipped to Germany.

On 19 February 1944, German soldiers loaded thirty-nine barrels of heavy water onto railroad cars and sidetracked them for the night. Armed guards lined the tracks from the plant to the dock. German reconnaissance planes scouted out the route continuously. Floodlights and soldiers surrounded the cars, and one soldier stood guard on top of each drum.

But at the dock there were no planes, no floodlights, and only one guard. On the ferry itself, the entire crew was below deck enjoying a rowdy game of poker. This was the break the Allies had been waiting for.

It was at this point that Haukelid, Sorlie and Lier-Hansen slipped aboard the ferry, their overcoats bulky with explosives. Lier-Hansen distracted a crew member, a fellow Norwegian with pleasantries, while Haukelid and Sorlie affixed the time-bomb in the bilge at the bow and then all slipped overboard and into the night. Within hours, they were safely on their way to Sweden.

The next morning, the railroad cars were brought to the dock and loaded onto the Hydro. At 10:00 the Hydro chugged away from the dock, right on schedule. At 10:45 the hidden alarm clocks rang. A huge explosion ripped an eleven-foot hole through the bow, just as the ferry crossed the deepest part of the lake. Four minutes later, Hitler’s entire stockpile of heavy water was 1,300 feet below the surface of Lake Tinn. Twenty-six civilians were killed in the blast, but the Allies hoped that millions of people were finally safe from the threat of Hitler’s bomb.

_ INCLUDEPICTURE “http://www.kidscastle.si.edu/channels/history/articles/images/historyarticle18_3.gif” \* MERGEFORMATINET ___

When the war ended, the Allies found the dismantled Norsk Hydro plant in Germany, together with uranium on the brink of going critical. The only thing missing was approximately seven-hundred liters of heavy water. Meanwhile, American scientists working on the Manhattan Project discovered something that German scientists had not: purified graphite was a perfect substitute for heavy water.