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Duration 00:27:40

Audacious Raids: Operations Grouse, Freshman, Swallow and Gunnerside 

Operations Grouse, Freshman, Swallow and Gunnerside were carried out by the Special Operations Executive (SOE) and the Norwegian Resistance in Norway in 1942-1943.

This talk examines these incredibly audacious missions that wrecked Nazi plans for an atom bomb, and which were described by the commander of German troops in Norway as ‘the most splendid coup [he had] seen this war’.

This talk was presented by Juliette Desplat, Head of Modern Collections, on Friday 4 September 2020.


Dr Juliette Desplat [00:00:01] Hello, everyone, and thanks for joining us today. I’m Dr. Juliette Desplat, I’m Head of Modern Collections at The National Archives, and today I’ll talk about some of the most audacious missions carried out during the Second World War: Operations Grouse, Freshman, Swallow and Gunnnerside.

[00:00:16] These operations were carried out in Norway by the Special Operations Executive (SOE) in 1942 and 1943, and were at the heart of the battle for a very rare commodity – heavy water – absolutely essential in the development of a nuclear bomb. There is a live Q&A at the end of this talk. So if you have any questions, do please use the chat function on the right hand side of your screen.

[00:00:40] To understand Grouse, Freshman, Swallow and Gunnerside, we have to go back to 1939 when in France Frederic Joliot-Curie and his team were using heavy water to conduct their experiments. They were racing against time to develop a nuclear weapon.

[00:00:55] So heavy water, heavy water combines d2o – deuterium oxide – with hydrogen deuterium oxide and ordinary water. I am told it looks, feels, tastes and smells like normal water, but is actually much denser, which makes it an efficient neutron modulator in nuclear reactions. Basically, if I understand it properly, slower moving neutrons like those pulsing through heavy water are much more efficient at splitting atoms.

[00:01:24] In 1939, it became apparent that the Germans were trying to get hold of the heavy water produced in Norway by the Norsk Hydro Elektrisk Kvalstofaktieselskab factory in Vemork about 65 miles west of Oslo. And if you are Norwegian, I do apologise. I’m going to refer to it as Norsk Hydro, not only because this is how it’s referred to in a lot of documents, a lot of the documents we hold at The National Archives, but also because, frankly, it’s awfully difficult to pronounce.

[00:01:55] In February 1940, the French Minister of Armaments, Raoul Dautry, approached this man, Jacques Allier, a member of the French intelligence service, The Deuxieme Bureau. Before the war, Allier had worked at the Banque de Paris et des Pays-Bas, who held most of Norsk Hydro’s shares. He was asked to negotiate their entire stock of heavy water – that was about 185 kilos – and to bring it back to France. According to a note written after the war and based on a conversation with Allier, he then set off for Norway with, as he put it, ‘all the paraphernalia of the hero of a spy story with the exception of a false beard’. Allier managed to secure the whole stock of heavy water and transported it to France, where it was entrusted to Joliot-Curie.

[00:02:42] When the Germans started marching on to Paris the heavy water cylinders were sent to Clermont Ferrand in central France, where they were kept in the vault of the French National Bank. They were then hidden in a prison cell in Riom, north of Clermont Ferrand and not too far from Vichy.

[00:02:58] When it became clear that France would fall, Allier enlisted inmates to carry the cylinders to his car and left for Bordeaux. He later reported there was a regrettable moment of tragicomedy when he had to threaten the warden with a revolver. In Bordeaux, Allier met with Joliot-Curie and two of his staff, Hans von Halban and Lew Kowarski. You can see them here in their lab. They were asked to accompany the precious cargo to Britain. Joliot-Curie refused to leave France so Halban, Kowarski and the heavy water embarked on SS Broompark on the 19th of June. They arrived in the U.K. on the 21st of June 1940, as you can see here on Kowalski’s registration card, and both joined the Cavendish Laboratory in Cambridge, where they were able to continue their research from Britain.

[00:03:49] As for Allier, he was summoned by the Vichy cabinet in August 1940 and had to confess then that the heavy water had left France. And this led to a rather farcical situation. The announcement provoked an argument between ministers, a number of rather crude insults were exchanged and he was treated to the spectacle of the Vichy cabinet at play with the old marshal trying to drown the din by flapping his arms.

[00:04:15] By 1941, as Norway was under Nazi occupation, word came through that the Norsk Hydro plant had increased production. This piece of intelligence came from Leif Tronstad, who’d worked at the plant before the war and joined the Norwegian resistance before having to escape to the U.K. It was Tronstad who initially pitched the idea of the raid on the plant, and he would take part in the planning of all the operations.

[00:04:41] According to a report on operations carried out by SOE in Norway, in July 1942 it was decided to be of the highest importance that the existing stocks of heavy water, deuterium oxide, at the Norsk Hydro works, Vemork, Norway should be destroyed, together with a plant essential for its production. And here is an aerial photograph of the plant in 1942.

[00:05:07] The war cabinet approached Combined Operations Headquarters, the Department of the War Office in charge of raids on the continent. A joint SOE combined operation seemed to be the best course of action. The first attempt was made in the autumn and winter of 1942. Operation Grouse started on the 18th of October 1942, when an SOE advanced party of four officers and NCOs of the Norwegian Independent Company were parachuted about 30 kilometres from the Norsk Hydro plant.

[00:05:38] Warrant officer Jens Anton Poulsson, Warrant Officer Knut Haugland, Sergeant Arne Kjellstrup and Sergeant Clause Helberg landed in Norway on the very day on which the infamous Kommandobefehl was issued by the high command of the German armed forces. This commando order stipulated that all saboteurs, military and civilians alike were to be executed without trial. So that gave us a very good idea of how dangerous the mission actually was. I don’t have photos of all of them, but here is Knut Haugland.

[00:06:11] When Grouse landed, the ground was, in Poulsson’s words, ‘a mess of stones’, and they were actually very lucky not to be wounded. Once on the ground, they started on a long trek through the Norwegian wilderness, during which each man had to make two journeys carrying about 30 kilos of equipment on severely rationed food. A day’s ration consisted of a quarter of a slab of pemmican. So that’s a mixture of talo, dry meat and dried berries. One handful of groats, one handful of flour, four biscuits, a little butter, cheese, sugar and chocolate. As Poulsson noted in his report, it was not much to travel on. And it was not an easy journey. The weather conditions were rather bad and the landscape was absolutely treacherous. Poulsson fell through the ice twice, and when you read his report, you can almost hear how exhausted and exasperated he was. ‘I fell through the ice, whilst crossing a river’, he wrote. ‘It was the second time’. When travelling on roads they also had to journey by night to avoid detection, making it even more dangerous.

[00:07:21] They had issues with their wireless set, and in London everyone was getting a bit nervous. And then on the night of November 1942, they finally made contact. Working at an altitude of some 1200 metres and a temperature continually below zero centigrade, they started transmitting reports on weather conditions and on German defences in the Rjukan area where the plant was located. The weather was extremely changeable. But on the 18th of November, when the moon finally seemed to enter a favourable phase, Operation Freshman could begin.

[00:07:59] On the 19th of November 1942, in weather conditions less than ideal, but still far better than those forecast for the rest of the moon, two aircraft left Scotland, each towing a glider carrying military personnel. The operation had two objectives: the destruction of existing stocks of heavy water and of at least part of the plant, and the collection of samples of the precious liquid. The geographical location of the plant made the operation extremely hazardous. It was impossible to land very close to the plant – it was too mountainous. But at the same time, they couldn’t land too far either. The men would’ve had to carry rush ins and explosives over very difficult roads covered in snow. A landing area was picked between the east arm of the Mosvatn lake and the Rauland Road. So this area here, about three miles from the dam, which you can see here, and you can see the factory here. Grouse would mark the dropping area with a triangle of red lights. The apex would point downwind and be marked by a white light flashing the letter L for London. They would guide the aircraft and glider thanks to a Rebecca/Eureka transponding radar.

[00:09:21] Now, there was also the slight issue of how to get the soldiers out of the country once their mission had been completed. Crossing the border into neutral Sweden in small groups of no more than three men seemed to be their safest bet, and very intricate and dangerous escape routes were designed. It was estimated that 12 to 15 men were necessary for the operation. To cover all contingencies, it was decided to duplicate the force. So in the end, each glider was to carry one officer, one sergeant and 13 other ranks, as well as two glider pilots.

[00:09:55] All the men coming from the first British Airborne Division received intensive training. But the mission was incredibly audacious and required extraordinary physical conditions and observation skills. The long night tow of about 400 miles was also very dangerous. And nothing like it had ever been attempted before. The operation was mounted in utmost secrecy. There was even a cover story that of the challenge of a company of American engineers for a Washington cup. It involved an approach marked by glider, a parachute, a demolition task and an entrance test. And this actually enabled the men to train and obtain supplies without being questioned in the U.K.. The Freshman men were given very clear operational orders. Any enemy sentry encountered was to be killed. If a man was wounded, he should be given morphine and left behind. If a man fell out, he was to be left behind. The orders stated, ‘whatever happens, someone must arrive at the objective to do the job. Detection is no excuse for halting’. And that was a bit harsh, and this was actually changed two days before takeoff. And the orders eventually stated that if through any misfortune, a glider landed in some totally unexpected place, the officer or senior passenger would decide whether it was practical to attack the objective or to try and escape to Sweden.

[00:11:30] When the morning of the flight came, morale was quite high and the men were even joking about the days to come. When the first aircraft glider tandem reached Norway, the weather took a turn for the worse. They were unable to locate their target and as the tow line started icing, and the plane’s fuel levels were dangerously low, the glider had to be released at sea. It crashed not far from the coast. The second tandem left 30 minutes after the first one. Both aircraft and glider crashed in Norway.

[00:12:06] On the 21st of November, the Germans made an announcement on the wireless. On the night of November 19th to 20th, two British bombers, each towing one glider, flew into southern Norway. One bomber and both gliders were forced to land. The sabotage troops they were carrying were put to battle and wiped out to the last man.

[00:12:32] All the survivors were caught by the Germans, tortured and executed. Details about their fate were only uncovered after the war. Some were shot, but others weren’t so lucky. Two were killed by morphine and water and air injections. One was strangled with a belt. Another was kicked and pushed downstairs, then shot. Their bodies were dumped into the fjord. A memorial stone was later erected in Stavangar to commemorate their heroic attempt. As later stated in a report, Operation Freshman was a gallant attempt which failed. Freshman was over and for the security of future attacks on the plant, all papers held at HQ RA First Airborne Division were burnt.

[00:13:18] The failure of Freshman was a hard blow for the Grouse men. ‘It was sad and bitter’, Poulsson later reported, ‘especially as the weather in our part of the country was splendid during the following days’. A report later stated ‘the fact that the air side of the operation was so nearly successful indicates the degree of enthusiasm, skill and courage of those who took part’. The first aircraft had passed very close to the target. Grouse’s Eureka did pick it up and the lights were lit. But when the plane was about two kilometres away, it changed direction and they were absolutely unable to see the lights because of the clouds. And this happened several times until the plane finally disappeared. Grouse waited as long as they could, but eventually had to give up. On the 21st of November 1942, transmitting the message that had been transmitted by the Germans on the wireless London wired to Grouse: ‘Keep up your hearts. We will do the job yet.’

[00:14:33] Grouse had actually remained undetected and they continued to transmit information. Because of the failure of Freshman, however, the Germans were aware that the plant was a target and they increased their defences. Grouse became Swallow and I quote, ‘continued their watch and signals amid snow and ice, short of food and with failing power and their W.T. set’.

[00:14:58] Food was a big issue for Swallow. The Swallow men had brought food from England. But half of it was gone by October. They managed to locally source scant supplies, but often had to mix moss with it. Around Christmas, things got a bit better on that front thanks to the hunting of wild reindeer. From then on, Poulsson reported, they lived on meat and he said, ‘ate every morsel of the animal in Indian fashion’. ‘One can live entirely on meat’, he said. ‘One gets vitamin C by eating the stomach with its contents. These contents, mixed with blood are a delicacy’.

[00:15:41] The targets and the objectives remained the same. The plant and its entire stock of heavy water needed to be destroyed. So a second attempt was made, in February 1943 – Operation Gunnerside. Lieutenant Fenrik Ronneberg selected five specially trained SOE Norwegian personnel: Knut Haukelid, Casper Idland, Hans Storhaug, Frederik Kayser and Birgr Stromsheim. You will remember that when preparations were being made for Freshman, it had been estimated that 12 to 15 men were necessary to carry out their operation. And this time there would only be six men. Much to their relief, Swallow volunteered to help. It’s also worth noting that, unlike the Freshman men, they were all Norwegian. Again, I don’t have photos of all of them. But here’s Knut Haukelid. The recommendation for award states, they were all volunteers who had full knowledge of the facts that the enemy were aware that the allies were interested in and had attempted to destroy production. That the area had been visited by the Reich Kommissar and by the German commander in chief in Norway. And that the local garrison had been strongly reinforced. They were also conscious of the fact that the landscape in which they would have to operate was incredibly dangerous. The target was in a deep valley. ‘So deep is the valley’, they said, ‘that throughout winter, the sun’s rays never reach Rjukan streets’.

[00:17:19] The Gunnerside men went through intensive training, physical training, of course, and shooting practise, but also demolition training on dummy plants and technical advice. The order was to destroy the whole stock of heavy water and all production facilities.

[00:17:36] On the 16th of February, 1943, they were parachuted in Bjornesfjorden, about 30 kilometres from Swallow’s camp. They swiftly unpacked their equipment and repacked what they needed. As the weather deteriorated, they took refuge in a hut where they found out that they were not at all where they thought they were. The weather remained absolutely horrendous until the 22nd of February when they could at last leave. They tried to pack as light as possible. But between the food, uniforms, equipment and explosives, the sacks weighed 25 kilos and the toboggans transported by ski weighed 30 and 40 kilos respectively. At 4pm on the 23rd of February, Gunnerside side finally met up with Swallow in a hut. Haugland went into hiding with his equipment to make sure communications could be maintained.

[00:18:36] On the 25th of February, they started making their way towards Norsk Hydro, skiing and walking and sometimes sinking into the snow up to their waist. They attacked they attacked the Vemork plant during the night of 27th to 28th of February. The combined Swallow Gunnerside force had been divided into two units: a support unit which would neutralise the German security guards, and a demolition unit which would place explosive charges in the basement to destroy the production facilities. They were all wearing British uniforms because they thought that if Britain, rather than the Norwegian resistance, was blamed for the attack then the local population may perhaps escape German retaliation.

[00:19:24] The demolition unit had plans to enter the plant through a side door. They had practised numerous times and they were extremely well prepared, but they hadn’t anticipated the door may be locked. Ronneberg and Kayser found an entrance tunnel and started laying out the charges. Idland and Stromsheim were less lucky and had to break through a window to get in. They had been provided with two minute fuses, but Ronneberg decided to shorten them to 30 seconds. It would make it more difficult for them to get out of the building, of course, but it would enable them to check whether they had succeeded, and really, this was the main thing.

[00:20:00] They all managed to get out of the room unscathed. And when they heard the muffled explosion, they knew their mission had been completed. The explosion sounded like a dull thud, Ronneberg later reported. And at that moment, a German came to the door, flashed a torch, and thankfully disappeared back into his hut.

[00:20:21] A report transmitted from Stockholm shortly after the operation stated: ‘They came in civilian clothes to Rjukan. But when they appeared at the factory, they were clad in British uniforms and had revolvers. They told the workers in perfect Norwegian to go up in the seventh floor of the factory building where no harm would come to them. Then they went up to the vital machinery of the factory, placed their explosive charges there, pulled out the fuse and lit it.

[00:20:49] The destruction was complete, as all the vital parts of the machinery were blown to pieces. 500 kilos of heavy water. The entire supply produced under German supervision was destroyed, along with all the equipment used to produce it. It was estimated that the plant would be put out of action for between eight and 12 months. After the explosion, the men regrouped outside of the plant and skied towards Rjukan. Once on the plateau, the group split up again.

[00:21:24] Of the combined party of 10 officers and men, five managed to cross the Swedish border on the 18th of March after a 500 kilometre ski trek over ridges and across valleys varying from 1000 metres to 150 metres, crossing the rivers by ice, bridges or boat, and struggling through almost primeval forests as they neared the border. The others remained behind, including the wireless operator who kept transmitting. The operator reported that General Falkenhorst, the commander of German troops in Norway, had visited the plant shortly after the attack. Which he at once ascribed to personnel from Britain. The team had been wearing British uniforms, as I said, and had left a British machine gun behind, ready to indicate British involvement. Falkenhorst also declared that it was the ‘most splendid coup he’d seen this war’.

[00:22:24] As early as August 1943, however, the Vemork plant had been repaired and production had started again. As it was still vital that the production of heavy water should be stopped, a choice had to be made between yet another sabotage operation or a straightforward bombing attack. A bombing attack seemed to be the only way to ensure substantial damage. But the deputy chief of air staff didn’t think it would work.

[00:22:53] The plant was quite small and a low level attack was impossible because of the hills surrounding it. Besides, all production facilities were in the basement, so very difficult to reach. A commando operation, on the other hand, seemed exceedingly dangerous as the Germans had substantially increased security at and around the plant. SOE declared it was too risky to carry out another attack, so the Americans were informed of the situation. And the American Air Force attacked on 16th and 18th of November, 1943. Swallow reported on the 30th of November, ‘Vemork, completely destroyed, will hardly be able to start production again during the war’.

[00:23:40] The Germans were convinced that other raids on the plant would occur. And they decided to move the remaining stock of heavy water to Germany. Knut Haukelid, who’d stayed in Norway after Operation Gunnerside, was ordered to stop the convoy. On the 20th of February 1944, a train carrying the cylinders of heavy water left Rjukan. Haukelid and his team of saboteurs had realised that, as the Germans had considerably increased the frequency of their aerial reconnaissance missions, the only way for them to succeed was to sink the ferry transporting the train coaches across Lake Tinn, one of the deepest lakes in Europe. Having been warned the train would leave on the 20th, the Norwegian team broke in to the ferry the night before. Then they were spotted by a guard, but managed to convince him that they were only workers and merely wanted to sleep aboard. They managed to plant explosive charges and to leave the ferry otherwise undetected. At 10:30, SF Hydro sank to the bottom of the lake, 430 metres deep.

[00:24:53] The battle for heavy water had been won. Long after the end of the war, when Joliot-Curie was not only a nuclear scientist but also an international communist, MI5 operatives noted that ‘it was impossible to give in a few lines an idea of his scientific work’. The SOE did give it a good shot in 1942. The application of heavy water, they said, was both Churchill’s and Hitler’s real secret weapon and bands of scientists were engaged in a race for the final result. While the American raid gave the Vermork plant the coup de grace, scientists like Halban, Kowarski or Joliot-Curie couldn’t have remained ahead in that race without the men involved in Operations Grouse, Swallow, Freshman and Gunnerside.

[00:25:43] The recommendation for award states, ‘where the essence of an operation is teamwork, the singling out of individuals for recognition is both difficult and invidious’. The above recommendations pay tribute to all who were intimately concerned, while recognising the weight of responsibility which was spawned by the leaders of both parties, advance and follow up, and by the wireless operator. Poulsson and Ronneberg were awarded the Distinguished Service Order, Haugland, Igland and Haukelid the Military Cross. Helberg, Kjellstrup, Kayser, Storhaug and Stromsheim the military medal. In London, Tronstad and Wilson were awarded OBEs. All the Norwegians were also awarded the Krigskorset med sverd, Norway’s highest military decoration.

[00:26:40] The actual impact of Grouse, Freshman, Swallow and Gunnerside on the outcome of the war and on the German atomic bomb programme remains difficult to assess. We now know that Germany was actually a long way from being able to produce a nuclear weapon. But the allies didn’t know this. And these operations were truly the most daring conducted in Norway. As the Ministry of Economic Warfare put it in 1943, ‘I hope you will agree with me that the story is a particularly good one’.

[00:27:11] If you’re interested in SOE operations in Norway, I couldn’t recommend enough Tony Insall’s excellent book Secret Alliances. And if you’re interested in audacious raids in general, we at The National Archives have produced this book on Audacious Missions of the Second World War. Thank you very much for listening. And don’t forget, you can ask questions using the chat function on the right hand side of your screen. Thank you.