Foiling the Nazi Atomic Bomb

How close were the Nazis to developing an atomic bomb? The reality of a Nazi atomic bomb was foiled in large part due to the great bravery of British and Norwegian commandos in 1942 and 1943.

The Race is On

In December of 1938 an experiment by German physicist Otto Hahn led to the discovery of atomic fission. In the following months, physicists around the world realized Hahn's discovery could lead to a successful chain-reacting uranium pile. The theoretical possibility of a super-explosive, an atomic bomb, was closer to becoming a reality. In April 1939, Professor Paul Harteck and Dr. Wilhelm Groth sent a letter to the German war office stating that the country that first exercised the use of atomic energy "has an unsurpassed advantage over the others." Soon after receipt of the letter the Nazi Germany government began serious atomic energy research.

In May of 1939 intensive fighting between Japanese and Russian troops developed along the Manchurian and Outer Mongolian border. The three-month long conflict foreshadowed the coming of another global conflict. In August of 1939, weeks before Hitler attacked Poland, Churchill understood the importance of the yet to be developed atomic bomb. In letters to colleagues he clearly demonstrated that he was aware of man's ability to bring to the world "new explosives of devastating powers." His intelligence sources were correct in reporting to him that the practical use of such a super explosive would not be put "into operation for several years."[i] However, he clearly realized six years before the atomic bombs that would shake Japan that "the human race is crawling nearer to the point where it will be able to destroy itself completely."[ii] Within the same month of 1939 Albert Einstein, with help from Hungarian physicist Dr. Leo Szilard, sent his famous letter to President Roosevelt stating that a "nuclear chain reaction in a large mass of uranium" could create "extremely powerful bombs of a new type."[iii] Dr. Szilard, a Hungarian Jew fearful that the Germans may develop an atomic weapon, was one of the first physicists to understand the principles of atomic chain reaction and appreciate what such power could do in the wrong hands. Einstein's letter was the driving force in Roosevelt's creation of a special committee to investigate the military implications of atomic power. He approved uranium research in October of 1939, one of many decisions that led to the creation of the Manhattan Project. The race for the atomic bomb was on.

Codename Tube Alloys

In June of 1942 Churchill and Roosevelt met in Washington D.C. to discuss, among other things, the issue of "Tube Alloys," the code name for the atomic bomb. It was agreed that German nuclear research was probably ahead of the Western Allies by as much as two years. The Germans had stopped exporting uranium from Czechoslovakia and had been furthering their research with a substance called "heavy water." Since the Nazis controlled Czechoslovakia, they were able to retrieve uranium at any time. The Belgian Congo, Canada, and Czechoslovakia were some of the very few places where uranium was mined.

Heavy water, sometimes called deterium oxide, is unique be­cause it contains atoms of double atomic weight. This charac­teristic slows down neutrons in uranium 235 and facilitates a chain reaction of exploding atoms that produces plutonium, a fissionable element and basis of the atomic bomb. Heavy water is not a component of the atom bomb, but it was essential in experiments with substances required for use in the manufacture of the bomb.[iv]Heavy water is created with enormous amounts of electrical power. During the war there was only one hydro-electric plant in the world capable of creating large amounts of this substance, and that was the Norsk Hydro plant at Vemork, Nor­way, a country occupied by the Nazis since 1940.

Churchill and Roosevelt agreed to pool their countries' ef­forts in nuclear research. However, neither country had developed a large enough supply of heavy water, so research would be done with a graphite-uranium pile instead of the uranium-heavy water pile used by the German. In case the graphite method proved fruitless a heavy water plant was to be built in British Columbia.

MI6 Plans a Commando Attack

MI6 Director Stewart Menzies put Lt. Cmdr. Welsh, the chief of the Norwegian country section of MI6, in charge of a commando attack on the Vemork plant. Welsh was convinced he could find a way to destroy or cripple the plant.

Though many Norwegian scientists had fled Norway when the Nazis took control, Professor Leif Tronstad, designer and con­struction supervisor of the Vemork plant, stayed in Norway and sent to London a large amount of industrial information about the German's intentions of increasing production of heavy water at the Norsk plant.

His activities were cut short in September of 1942 when a double agent informed Tronstad that the Nazis were aware of his illegal transmissions. Tronstad reluctantly left his family and country and fled to England.

In October of 1941 the underground secret intelligence service in Denmark alarmed MI6 when they sent a telegram outlining the details of a meeting between Danish physicist and a German scientist Werner Heisenberg. The conversation led the Danish physicist to believe that the Nazis were close to developing the ultimate weapon - the atomic bomb.

Tronstad was made head of Section IV of the Norwegian High Command in London. He was in charge of intelligence espionage and sabotage, but none of his activities were as important as his communication with his friend and colleague Dr. Jomar Brun, the chief manager of production at the Vemork plant. Tronstad wished to establish a line of communication with his old friend.

The contact was made when six of Tronstad's men, all Norwegian natives, were parachuted onto the cold, desolate Hardanger plateau near Vemork, March 29, 1942. Head of the mission was Einar Skinnarland an athletic skier who had excellent knowledge of the area. Skinnarland was successful in contact­ing Brun. Tronstad and Brun exchanged messages by secret writings through Stockholm. Tronstad wondered if it were pos­sible to transport a large amount of heavy water to London by landing a British plane on a frozen lake near Vemork, but Brun felt it was impossible. Brun began to sabotage the production of the heavy water by adding cod-liver oil to the water. This stopped production for several days at a time. Brun and Skin­narland collected photos, drawings of the countryside as well as specific details about the plant. They microfilmed this data, concealed it in toothpaste tubes, and had the tubes delivered to Tronstad via Sweden.

MI6 studied the information. Menzies approached the Joint In­telligence Committee with a proposition that the Vemork plant be destroyed as soon as possible. Quickly plans were made to send a commando team of paratroopers into Norway. The plan was called "Operation Freshman."

Operation Freshman

Thirty-four commandos of the First Airborne Division were to land in two Horsa gliders on the Hardanger plateau and then proceed by bicycle to the plant. They were to kill the German guards on the suspension bridge that led across a gorge to the plant. After they destroyed machinery and stocks of heavy water they were to split into groups of no more than three and make their way to Sweden. If possible they were to bring back any of the 200 cubic centimeter steel flasks of heavy water that they could manage.

There was doubt that the mission could be successful. Many reasons were cited by Tronstad: Norway's terrain was not suitable for glider landings, weather was harsh and unpredict­able, the folding bicycles would prove to be worthless in the event of snowfall and the men were expected to travel 400 miles to the Swedish border.

Bombing the plant was an option, but Tronstad opposed this also. If the plant's liquid storage tanks were hit the entire Rjukan population could be in grave danger.

On October 18, 1942 four Norwegians led by Jens Poulsson were flown over the Hardanger plateau and dropped by parachute. They were to provide weather reports, operate a navigational aid that would help guide the Operation Freshman aircraft, light up the landing area with beacons, guide the troops to the Vemork plant and make reports by a portable telegraph unit.

Tronstad ordered Brun to leave Norway. Brun reluctantly agreed. He and his wife carried two kilos of heavy water and poison ampules in case they were caught by the Nazis. They traveled by train to Oslo and from there were safely flown to London.

The day the Bruns took off for London, November 9, 1942, the Poulsson team made contact with Tronstad and London. After great hardship they had made their way to an abandoned cabin on the plateau and reported among other things that the navigational aid had been tested and was operating correctly. As the Norwegian telegraph operator made his report the London operator grew suspicious. Every operator has an individual style of manipulating the sending key. These idiosyncrasies were known as the operator's fingerprints and a record was made of them for security reasons. As the Norwegian operated his sending key, with fingers numb with cold, the London operator recognized an unfamiliar pattern and thought the Ges­tapo had captured the sending station. The London operator made security checks, and the Norwegian replied satisfac­torily. There was one final question that had to be answered with a previously agree upon answer. "What did you see walk­ing down the Strand in the early hours of January 1, 1941?" The Norwegian replied with the correct answer, "Three pink elephants." MI6 in London knew all was well.

November 19, 1942 the commandos of Operation Freshman, all volunteers in their early twenties, boarded two Horsa gliders at Wick airfield in Scotland. Those at MI6 that were skepti­cal the mission would be successful had their reservations confirmed. The second tandem of plane and glider both crashed. All four men were killed on the Halifax plane. Ger­man troops reached the crash site of the glider the next morn­ing in the mountains northeast of Helleland, Norway. There were fourteen surviving commandos. The Nazis interrogated them and then followed a recent edict by Hitler that "crews of sabotage planes are to be shot." The Germans executed the commandos by firing squad.

The first Halifax-Horsa tandem made its landing site where Poulsson's team heard the Halifax overhead. But the Halifax crew didn't realize where they were and had to turn back toward the proposed site. By the time the Halifax crew real­ized they had over-shot their target they decided to return to Scotland since there was only enough fuel to do just that. The planes began picking up ice and the towline snapped. The Halifax crew radioed London that the Horsa glider had plunged into the sea, but actually the glider had crashed into the mountains near Lyse Fjord. Eight were killed in the crash. The Wehrmacht and Gestapo headquarters for interrogation. When it was found that they were too injured to be of any use they were poisoned by a German medical officer. When a map with Vemork circled in ink was found there was no question as to the mission of the men. The five remaining men were all shot.

Operation Gunnerside

The glider disaster was a hard blow to MI6. Col. Jack Wilson, the chief of Norwegian Section, had always been against the glider mission, but felt they had a good change with paratroopers. He selected Norwegian Lt. Joachim Ronneberg to select five expert skiers from the Royal Norwegian Army`s volunteers. They were to join Poulsson and his men (now code-named the Swallows) on the plateau. This second attack was named Operation Gunnerside.

Now MI6 was in the services of Dr. Brun who had built a model of the plant. He was able to answer most of the questions from the commandos about details of the plant. The commandos were trained at a special school in Scotland. The objective was to link up with the Swallows, and proceed to the plant. When they reached the plant they were to destroy the eighteen stainless steel cells of heavy water.

On February 16, 1943 the men parachuted to within 28 miles of the Swallow's hideout. After weathering a blizzard they sighted two of the Swallows. Everyone was in poor condition, especially the Swallows who were weak from malnutrition and hobbled with frost bite.

The Gunnerside party began planning the attack. The only way to get into the plant without alerting the guards would be a dangerous descent into a gorge in front of the plant. Then they would climb a 500 foot face of the outcrop that the plant was built on.

On the evening of February 27 the nine men skied to the plant and descended into the gorge. They crossed the stream and began the difficult climb up the gorge. They reached the top about midnight, crept through a minefield and avoided the Ger­man guards. Two men entered the basement of the plant by crawling through a cable duct and then unlocked a door. There was only one workman in the plant, a Norwegian. The comman­dos, dressed in British uniforms, laid the charges on the eighteen cells that produced the heavy water. They set the fuses and told the workman to find safety on one of the upper floors.

All nine commandos left the plant and scrambled down the gorge, and as they did the charges went off destroying the cells. The German never saw the commandos until they were on the other side of the gorge. All escaped the German pursuit by skiing through a fierce blizzard. Two of the commandos stayed on the Hardanger plateau and the others skiied 250 miles to Sweden.

The mission was a success. It took the Germans six months to get the plant in good enough condition to produce heavy water again. On November 16, 1943, the American high command or­dered the 8th Air Force to bomb the plant. The plant was suf­ficiently damaged to convince Goering, minister of the German atomic program, to move the heavy water production from Vemork to Germany.

Skinnarland radioed this information to London in November. At the end of January 1944 Skinnarland found that the Germans were going to transport approximately 14 tones of heavy water in various forms of concentration. The heavy water was stored in drums marked "Potlash Lye." The Germans began to transport them by rail.

Knut Haukelid, a member of the Gunnerside operation, and Alf Larsen, the chief engineer at Vemork, planned a way of sabotaging the transportation. Larsen had found that the Ger­mans were to ferry the load across Lake Tinnsjo in its journey to Germany.

Haukelid made a journey on the ferry and concluded that it could be sunk if explosives blew a hole in the bow about forty-five minutes into the journey. He figured a plastique charge of 18 pounds would sink the ferry but leave the pas­sengers as unharmed as possible.

On February 19, 1944 the night before the shipment was to ar­rive, Haukelid and two of his men set the charge with an electronic detonator and timed fuse. It was set for 10:45 a.m. The next morning SS guards helped transport the shipment onto the ferry and by 10 a.m. the ferry left with fifty-three passengers. Forty-five minutes later an explosion rocked the ferry and in five minutes the ferry, the railway wagons went to the bottom of the lake. Twenty-six passengers were drowned. Only three canisters were salvaged.

Thus came to an end the real threat of the Nazis ever develop­ing the atomic bomb.

Sources:

Churchill, Winston. The Gathering Storm, Houghton Mifflin, Boston, 1948, pp. 386-7.

Hyde, Harford Montgomery. The Atom Bomb Spies, Atheneum, New York, 1980, p. 71-72.

http://www.em.doe.vog/timeline/aug1939.html (U.S. Department of Energy Office of Environmental Management Historical Document, August 1939).