Analysis and Summary of the Four Major Attempts to Disrupt Germany’s Supply of Heavy Water
by
Daniel
From 1941 through 1945, Germany occupied Norway and controlled the only facility in the world which could produce significant quantities of dideuterium monoxide (heavy water). Heavy water is an excellent moderator for nuclear reactors, because the neutrons which both cause and are produced by the splitting of Uranium-235 are not absorbed when they move through heavy water, and instead are merely slowed. Normal water absorbs the neutrons, halting the reaction. With access to plentiful moderator, the Germans would be able to produce Plutonium from the Uranium blend accessible to them. The Plutonium produced could then be used for an atomic bomb. The British had intelligence from Leif Tronstad, a member of the Norwegian resistance who had been supplying information to the British, about German interest in the Norsk Hydro electrolysis, Vemork, which was the world’s largest producer of heavy water. Tronstad and another Norwegian named Jomar Brun had created the system which Vemork used to purify heavy water from regular water, where the concentration of heavy water is 0.024 ppm (parts per million).[1] Brun also ran the heavy water production, giving him access to information on the for heavy water, information that Brun gave to Tronstad, who then gave the information and his analysis of it to the British.[2] Norsk Hydro engineer and SOE agent Einar Skinnarland had also been supplying information to the British about Norsk Hydro operations.[3]
With their fears of a German atomic bomb reinforced by Tronstad’s intelligence, the Allies, launched four separate attacks, mainly through Special Operations Executive (SOE) against Germany’s heavy water supply over a period of approximately three years: 1) Operation Freshman, a failed glider landing of Royal Engineers on November 19, 1942 meant to attack Vemork; 2) Operation Gunnerside, a team of Norwegian SOE operatives sent to blow up the high-concentration cells at Vemork that purified the heavy water, on February 28/March 1, 1943, 3) A strategic bombing attack against Vemork led by the United States Army Air Forces (USAAF) on November 16, 1943; and 4) Sinking the ferry D/F Hydro which was carrying most of the remaining heavy-water supply on February 20, 1944.
Vemork, Telemark, Norway
Vemork is in the Telemark region of Norway, directly off of the southeast corner of the Hardanger Plateau (Hardangervidda). To the north of Vemork, there is a deep valley with steep sides and a river running through it.[4] There is a single-lane suspension bridge crossing the valley, there is an access road on the south side of the plant, and on the Hardangervidda there can be snow on the ground from mid-October through early June.[5] On the Hardangervidda the temperatures can reach below -30℃.[6] The Hardangervidda has wild and barren terrain, and at the time had no permanent living quarters on it, only hunting cabins. The Hardangervidda has an elevation of around 3,000 feet above sea level (ASL). There are high winds on the Hardangervidda and the weather can rapidly shift from sunny to a snowstorm of subzero temperatures.[7]
Operation Grouse & Operation Freshman: Glider Infiltration
Operation Freshman was the plan to use a team of Royal Engineers, guided by a small team of Norwegian SOE operatives, to attack the basement of Norsk Hydro, where the heavy water was concentrated. The operation that landed the team of Norwegian operatives on the Hardangerviddda was called Operation Grouse. The Grouse team would set up a landing site for the two gliders that would be carrying the Royal Engineers, Operation Freshman. The gliders were towed by Handley-Page Halifax bombers from the Royal Air Force, which used either visual confirmation or a navigation system called Eureka to find the target to drop the Grouse men. The men would be led by Jens-Anton Poulsson, who had been an NCO in the Norwegian Army.[8]
Twice during September 1942, the Grouse team was unable to land in Norway. The first attempt was foiled by the engines failing and the second attempt was unsuccessful due to reports of fog over the landing site, preventing them from being able to identify it. On October 18, 1942, the Grouse team was given the go-ahead to proceed with the mission. The men parachuted from 1000 ft and landed in a snowstorm on the plateau.[9] They sustained no injuries on landing and they agreed to prepare their landing site for the gliders at the Skoland Marshes. The gliders were scheduled to land on the next full moon, four weeks later.
There were food shortages and the battery supplied for their radio was twice as heavy, and thus more powerful, than the battery they had requested; when they attempted to charge it, it burned out their hand generators, leaving their radio inoperable. After securing a new battery, the Grouse team made contact with London confirming their safe landing on November 9, 1942. Three days later, the Grouse team informed London of the local conditons and landing site they had prepared for the Horsa gliders to be used in Freshman.[10] On November 20th, the two gliders, together carrying the 34 commandos took off from London. While over the coast of Norway, the towrope of one of the gliders broke and the pilot managed to fly it further inland. After severe turbulence, the glider crashed killing eight of the men, with five remaining uninjured.
The second bomber was flying low in order to identify the landing site, was on course to collide with a mountain but managed to avoid the impending collision by releasing the glider. The bomber tried to search for the glider, and was unable to avoid another mountain and crashed.[11] The second glider landed in a controlled crash in a wooded valley and three men died in the crash. Some of the men were injured and went to a local farmer for help, whose father was the sheriff. The sheriff agreed to contact the doctor, but also informed the German commander of the presence of the Royal Engineers, which were all interrogated and then executed in conformity with the recently changed German protocol to grant no quarter to any captured commandos.
While operation Freshman was ill-fated, it resulted in the loss of both glider teams and a bomber crew, the dangers of the Nazis completing an atomic bomb warrant the losses that occurred had there been thourough planning. However, operation Freshman was not thoroughly planned, with the British being so ignorant of the conditions in Norway that they were considering sending bicycles for Freshman, which was to happen in November when the Hardangervidda would be snowbound.[12] The idea of using gliders was an efficient solution for transporting the explosives with more tame weather conditions and geography, however in the hash and perilous environment of the Hardangervidda in winter, the Horsa gliders used in Freshman proved to be unsuitable for the conditions and crashed along with one of the Halifax bombers. Given the plan for Freshman, the reason for its failure was the Norwegian weather. Visibility was poor and the cold froze and broke the towrope on one glider. Had the environment and terrain been more like that in western Europe, Freshman would have had a much higher chance of success given the more mild weather there. More intelligence could have shown how poorly suited gliders were to the conditions.
While the use of a large group of Royal Engineers is not optimal, given that the British command insisted on it, if operation Freshman had been replaced with a smaller group of British soldiers, consisting of only five Royal Engineers, plus four subunits similar to modern fireteams. They would be named Fireteams A, B, C and D, with sizes ranging from four to five men. Fireteam A would consist of a sniper armed with a Pattern 1914 Enfield rifle, two men armed with Colt Monitor machine rifles, and a commander with a Thompson submachine gun. Fireteam B would consist of two Bren light machine gun crews of two men each, and a commander with a Thompson. Fireteam C would contain a grenadier armed with a Colt 1911 pistol, one man armed with a Colt Monitor, two men wielding Thompsons, and a commander also carrying a Thompson. Fireteam D would consist of four men, two men wielding Boys anti-tank rifles, and two with Colt Monitors.
The attack would be supported by six Blackburn Skua, each carrying a 500 lb bomb; and three Grumman Wildcats serving as escort fighters. Two of the aircraft would strike first with their bombs, creating a diversion for Fireteams A and B, who would charge the bridge and form a bridgehead, with Grouse team and Fireteam D guarding the opposite end of the bridge, under the command of Poulsson. Then Fireteam C and the team of Royal Engineers would fight their way into the room containing the high-concentration cells where they would lay explosives and destroy the cells, while Fireteam C covered them while they planted the explosives and during their retreat. Following the detonation of the explosives, two of the Skua still carrying bombs would then try to bomb the high-concentration room to maximize damage to the heavy water machinery. Then the men would retreat across the suspension bridge, which the final two Skua would attempt to destroy with their bombs after the men had crossed to slow the German pursuit. The men would commandeer trucks and drive to the coast, where they would seize a small ship and sail with it to Scotland.
Review of Freshman against the Six Principles of Special Operations plus Moral Factors
Operation Gunnerside: Basement Raid
Following the failure of operation Freshman, Wilson and Tronstad decided to create a small group of Norwegian-native commandos to join with Grouse, and attack Vemork. This new operation, named Operation Gunnerside, would be led by Joachim Rønneberg, with four men of his choice plus Knut Haukelid as his second-in-command, who had been requested by Tronstad.[13] The four men Rønneberg selected were Birger Strømsheim, Fredrik Kayser, Kasper Idland, and Hans Storhaug. After multiple delays, The Gunnerside men parachuted onto the Hardangervidda on February 16, 1943. They met with the Grouse team on February 22. Together, the men decided that they would attempt to scale the ravine and cross the frozen Måna River, which ran below Vemork, to both attack and escape.[14] Then on February 28, 1943, at 2000hrs, the men, led by Helberg, left the hunting cabin they were staying in towards Rjukan Valley, beyond Vemork. The covering team, led by Haukelid, and demolition team, led by Rønneberg, joined-up and at 0045 hrs, March 1, Rønneberg and Kayser entered the building where the heavy water high-concentration cells were through a cable duct, which led to the room next to the high-concentration cells. They surprised the one worker in the room and proceeded to lay the explosives. At 0115 hrs, Rønneberg lit the fuses, the explosives went off, and the men escaped down into the Rjukan Valley and were crossing the Måna River when the sirens at Vemork went off, although no searchlights were turned on. The men then ascended the opposite side of the valley and escaped towards a hut near Lake Langesjå at 0500 hrs, March 1.[15]
By destroying the heavy water cells, it would take approximately one year after being rebuilt for Vemork to independently[16] begin producing high-concentration heavy water. This is because the high-concentration cells at Vemork worked by feeding the heavy water from one cell to the next, mixing it with lower concentration heavy water, which would then be at a higher concentration. This process required the stores of heavy water to be used in order to start production again, severely hampering its efficiency. Gunnerside managed to achieve the destruction of the high-concentration cells without the loss of any life, Norwegian or German. The plan was executed efficiently and swiftly, without any need for the Gunnerside men to fight to get in or out of Vemork. While Rønneberg was laying the explosives, Strømsheim and Idland crashed through the window as they had decided to enter the room by force, which had the potential to compromise their security by alerting the guards of their presence if one happened to notice the light coming from the window.[17] There was one close encounter when Haukelid and Poulsson were guarding the German barracks and a soldier came very near to revealing their hiding spot with his flashlight, but luckily he did not see them and left, preserving the security of the operation.[18] The operation had limited goals and achieved them, leaving me no suggestions for modifications that I believe could improve the effectiveness of the raid.
Review of Gunnerside against the Six Principles of Special Operations plus Moral Factors
USAAF Bombing Raid
Following Gunnerside, three options were considered for a second attack on Vemork: (1) interfere with production by internal sabotage, (2) a second attack similar to Gunnerside, and (3) strategic bombing.[20] A daytime precision bombing attack was selected as it was likely to be the most efficient, as with the increased security at Vemork following Gunnerside, it would be difficult to launch a similar operation.[21] The order to attack was sent to USAAF General Ira Eaker, commander of the 8th Air Force. On the morning of November 16, 1943, 388 B-17 Flying Fortresses and B-24 Liberators were bound for Norway, with 178 of them going to Vemork. The bombers were to attack Vemork no earlier than 1145 hrs, as that was when the workers were taking their lunch break. The bombers struck Vemork and its surrounding area with a total of 711 1,000 lb bombs. The bombs tore the bridge in half, destroyed and damaged water pipelines, damaged the power station including the destruction of two generators, and sheared-off the west corner of the hydrogen plant. Several houses were leveled bombs, which caused flying debris and fire to spread the destruction.[22] The bombing raid did stop heavy water production temporarily,[23] however the high-concentration cells remained undamaged, allowing production to resume shortly.[24] The topography of Vemork and its surrounding areas, the limited precision of high-altitude bombing, and the German smoke generators made it unlikely for such a raid to succeed.[25]
Although 21 Norwegians were killed in the bombing, there was no clear intelligence stating that the Germans had stopped pursuing an atomic bomb or were not trying to create other radioactive weapons. The potential costs of allowing the Germans to continue with their atomic research were far greater than those of a bombing raid.[26] By carrying-out the bombing during the workers’ lunch break, the risk of civilian casualties would be decreased, although because the bombers had to loiter to delay the bombing until 1145 hrs, the Germans prepared defenses and managed to kill two bombers.[27] To reduce the civilian casualties, the operation could have been conducted by two squadrons of de Havilland Mosquito bombers, with each aircraft carrying a 1,900 lb General Purpose bomb. These bombs would have had better penetration, and the Mosquitos could have hit their targets with much greater precision, resulting in reduced collateral damage. This would also have allowed for a smaller attacking force, which would mean reduced resource expenditure.
Review of the bombing of Vemork by the USAAF against a subset of the Nine Principles of War
Sinking the Ferry D/F Hydro
On December 11, 1943, Dr. Kurt Diebner, a physicist working in the German atomic program, visited Norsk Hydro’s Oslo headquarters. Diebner was told by several officials that Norsk Hydro would not be able to continue production, “as as they could ‘expose the company’s workers to further attack, nor invest another fortune in rebuilding a plant that would be lost in the event of a new air raid.’ Diebner agreed.”[28] He wished to move all of the high-concentration equipment and all stores of heavy water at any concentration, to Germany. There, a new facility would be constructed, giving him access to the heavy water he required, both as a moderator, and a completely different use directly as an explosive. It had already been shown by physicists that when two deuterium atoms, moving at high speeds, collided with each other, it released pulses of energy. Diebner and his team of physicists had begun creating experiments that would use shock waves from shaped charges to squeeze deuterium atoms together, giving Germany a second option for an atomic weapon.[29]
On January 29, 1944 Einar Skinnarland received a message from Tronstad: “It is reported that the heavy-water appliances at Vemork are to be dismantled and transported to Germany. Can you obtain confirmation of this? If it is true, are there any possibilities of preventing the transport? It is a matter of great importance.”[30] Skinnarland visited Vemork engineer Rolf Sørlie, who was a member of the resistance and was able to confirm that Vemork was to be disassembled, and said that the heavy water stocks were to be shipped out first.[31] Skinnarland and Sørlie met with Haukelid, and on February 8, they received orders from Tronstad to destroy as much heavy water as possible, and try to cause minimal harm to civilians. Based on information provided by Sølie, it was determined that they would sink the ferry that would carry the heavy water across Lake Tinnsjø.
On February 10, they were given approval from London to sink the ferry. The men settled on using a time bomb to sink the ferry before it could reach the shore. If they failed to stop the shipment of heavy water from reaching Germany, the Germans would have direct access to heavy water for their atomic research. Haukelid and his men needed to create a hole in the ferry large enough to sink it quickly, leaving the 5,000 gallons of heavy water practically irrecoverable at a depth of 1,300 feet below the surface,[32] while also leaving time for civilians to escape.[33] Sørlie brought along a new recruit he had found, named Knut Lier-Hansen. He was a former Norwegian Army sergeant and worked for the Milorg, the Norwegian resistance, as a weapons instructor, spy, and radioman. Lier-Hansen recruited a man named Olav Hansen to drive them, who after much difficulty, managed to start his car at 0100 hrs, February 20, and then drove Haukelid, Sørlie, and Lier-Hansen the 7¼ miles to within a ¾ mile radius of the ferry dock, at Mael.
The three saboteurs entered the D/F Hydro’s passenger saloon, and were about to open the hatch to the bilge, when they heard a crewman approach, Haukelid and Sørlie hid from him, although Lier-Hansen recognized the man as John Berg from the athletics club. He happened to be sympathetic to the resistance, so Haukelid and Sørlie came out and then Lier-Hansen told him they needed to hide something from the Germans. Berg agreed, and Haukelid and Sørlie entered the bilge, and layed a 12ft tube of plastic explosive, which weighed 19 lbs, in an almost full circle on the hull. Haukelid set the timer for 1045 hrs, wired the electric detonators to the clock circuits, set the alarm-clock hammer in the timer, and connected the detonator caps, completing the time-bomb. At 1045 hrs that morning, the explosives detonated and then the ferry sank. 27 people, including four German guards, survived; however, 22 Norwegians and four guards, did not. Four half-empty drums of heavy water were all of the stocks that surfaced.[34] The losses were high, although given what was at stake, destroying the heavy water had to be the primary goal, with minimizing losses a secondary priority. The plan to sink the heavy water and its execution was designed to minimize civilian losses while completing the mission, and the execution of the plan went without any trouble.[35]
Review of the Sinking of the D/F Hydro against the Six Principles of Special Operations plus Moral Factors
“SOE’s achievements in successfully destroying the heavy water production facilities at the Norsk Hydro Plant in Vemork established the organisation’s reputation for the rest of the war.”[36] Diebner believed that the attack on Vemork was the main reason why the German atomic program did not achieve the necessary conditions to sustain a reaction. In May, 1945, a facility with almost a sufficient quantity of heavy water to develop an atomic bomb was discovered in Bavaria. Without precise knowledge of whether the Germans would have been able to create an atomic bomb before the Allies, the attacks launched by SOE provided insurance against the event that the Germans were on the course to develop an atomic bomb before the Allies.[37]
Sources
Footnotes
[1] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 21-22.
[2] Ibid., 35-38.
[3] Ibid., 54-55.
[4] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 46-47.
[5] “Weather statistics for: Hardangervidda nasjonalpark, Eidfjord (Hordaland),” Norwegian Meteorological Institute, accessed January 18, 2019, https://www.yr.no/place/Norway/Hordaland/Eidfjord/Hardangervidda_nasjonalpark/statistics.html.
[6] Ibid.
[7] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 81.
[8] Ibid., 67-106.
[9] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p.16, 46.
[10] Ibid., p. 17.
[11] Ibid, p. 23.
[12] “The Winter Fortress,” C-SPAN, published May 11, 2016, https://www.c-span.org/video/?409379-1/neal-bascomb-discusses-the-winter-fortress.
[13] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 106-112.
[14] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 35-47.
[15] Ibid., 46-47.
[16] Richard Rhodes, The Making of the Atomic Bomb. (New York: Simon & Schuster, 1986), p. 457
[17] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 166-167.
[18] Ibid., 168-169.
[19] Ibid., 166.
[20] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 205.
[21] Ibid.
[22] Ibid., 205-213.
[23] Ibid, 211-213.
[24] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 64-65.
[25] Ibid.
[26] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 213-215.
[27] Ibid., 210.
[28] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 218.
[29] Ibid.
[30] Ibid.
[31] Sabotage
[32] Ibid., 229.
[33] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 68-69.
[34] Ibid., 73.
[35] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 233-242.
[36] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 75.
[37] Ibid., 77.
With their fears of a German atomic bomb reinforced by Tronstad’s intelligence, the Allies, launched four separate attacks, mainly through Special Operations Executive (SOE) against Germany’s heavy water supply over a period of approximately three years: 1) Operation Freshman, a failed glider landing of Royal Engineers on November 19, 1942 meant to attack Vemork; 2) Operation Gunnerside, a team of Norwegian SOE operatives sent to blow up the high-concentration cells at Vemork that purified the heavy water, on February 28/March 1, 1943, 3) A strategic bombing attack against Vemork led by the United States Army Air Forces (USAAF) on November 16, 1943; and 4) Sinking the ferry D/F Hydro which was carrying most of the remaining heavy-water supply on February 20, 1944.
Vemork, Telemark, Norway
Vemork is in the Telemark region of Norway, directly off of the southeast corner of the Hardanger Plateau (Hardangervidda). To the north of Vemork, there is a deep valley with steep sides and a river running through it.[4] There is a single-lane suspension bridge crossing the valley, there is an access road on the south side of the plant, and on the Hardangervidda there can be snow on the ground from mid-October through early June.[5] On the Hardangervidda the temperatures can reach below -30℃.[6] The Hardangervidda has wild and barren terrain, and at the time had no permanent living quarters on it, only hunting cabins. The Hardangervidda has an elevation of around 3,000 feet above sea level (ASL). There are high winds on the Hardangervidda and the weather can rapidly shift from sunny to a snowstorm of subzero temperatures.[7]
Operation Grouse & Operation Freshman: Glider Infiltration
Operation Freshman was the plan to use a team of Royal Engineers, guided by a small team of Norwegian SOE operatives, to attack the basement of Norsk Hydro, where the heavy water was concentrated. The operation that landed the team of Norwegian operatives on the Hardangerviddda was called Operation Grouse. The Grouse team would set up a landing site for the two gliders that would be carrying the Royal Engineers, Operation Freshman. The gliders were towed by Handley-Page Halifax bombers from the Royal Air Force, which used either visual confirmation or a navigation system called Eureka to find the target to drop the Grouse men. The men would be led by Jens-Anton Poulsson, who had been an NCO in the Norwegian Army.[8]
Twice during September 1942, the Grouse team was unable to land in Norway. The first attempt was foiled by the engines failing and the second attempt was unsuccessful due to reports of fog over the landing site, preventing them from being able to identify it. On October 18, 1942, the Grouse team was given the go-ahead to proceed with the mission. The men parachuted from 1000 ft and landed in a snowstorm on the plateau.[9] They sustained no injuries on landing and they agreed to prepare their landing site for the gliders at the Skoland Marshes. The gliders were scheduled to land on the next full moon, four weeks later.
There were food shortages and the battery supplied for their radio was twice as heavy, and thus more powerful, than the battery they had requested; when they attempted to charge it, it burned out their hand generators, leaving their radio inoperable. After securing a new battery, the Grouse team made contact with London confirming their safe landing on November 9, 1942. Three days later, the Grouse team informed London of the local conditons and landing site they had prepared for the Horsa gliders to be used in Freshman.[10] On November 20th, the two gliders, together carrying the 34 commandos took off from London. While over the coast of Norway, the towrope of one of the gliders broke and the pilot managed to fly it further inland. After severe turbulence, the glider crashed killing eight of the men, with five remaining uninjured.
The second bomber was flying low in order to identify the landing site, was on course to collide with a mountain but managed to avoid the impending collision by releasing the glider. The bomber tried to search for the glider, and was unable to avoid another mountain and crashed.[11] The second glider landed in a controlled crash in a wooded valley and three men died in the crash. Some of the men were injured and went to a local farmer for help, whose father was the sheriff. The sheriff agreed to contact the doctor, but also informed the German commander of the presence of the Royal Engineers, which were all interrogated and then executed in conformity with the recently changed German protocol to grant no quarter to any captured commandos.
While operation Freshman was ill-fated, it resulted in the loss of both glider teams and a bomber crew, the dangers of the Nazis completing an atomic bomb warrant the losses that occurred had there been thourough planning. However, operation Freshman was not thoroughly planned, with the British being so ignorant of the conditions in Norway that they were considering sending bicycles for Freshman, which was to happen in November when the Hardangervidda would be snowbound.[12] The idea of using gliders was an efficient solution for transporting the explosives with more tame weather conditions and geography, however in the hash and perilous environment of the Hardangervidda in winter, the Horsa gliders used in Freshman proved to be unsuitable for the conditions and crashed along with one of the Halifax bombers. Given the plan for Freshman, the reason for its failure was the Norwegian weather. Visibility was poor and the cold froze and broke the towrope on one glider. Had the environment and terrain been more like that in western Europe, Freshman would have had a much higher chance of success given the more mild weather there. More intelligence could have shown how poorly suited gliders were to the conditions.
While the use of a large group of Royal Engineers is not optimal, given that the British command insisted on it, if operation Freshman had been replaced with a smaller group of British soldiers, consisting of only five Royal Engineers, plus four subunits similar to modern fireteams. They would be named Fireteams A, B, C and D, with sizes ranging from four to five men. Fireteam A would consist of a sniper armed with a Pattern 1914 Enfield rifle, two men armed with Colt Monitor machine rifles, and a commander with a Thompson submachine gun. Fireteam B would consist of two Bren light machine gun crews of two men each, and a commander with a Thompson. Fireteam C would contain a grenadier armed with a Colt 1911 pistol, one man armed with a Colt Monitor, two men wielding Thompsons, and a commander also carrying a Thompson. Fireteam D would consist of four men, two men wielding Boys anti-tank rifles, and two with Colt Monitors.
The attack would be supported by six Blackburn Skua, each carrying a 500 lb bomb; and three Grumman Wildcats serving as escort fighters. Two of the aircraft would strike first with their bombs, creating a diversion for Fireteams A and B, who would charge the bridge and form a bridgehead, with Grouse team and Fireteam D guarding the opposite end of the bridge, under the command of Poulsson. Then Fireteam C and the team of Royal Engineers would fight their way into the room containing the high-concentration cells where they would lay explosives and destroy the cells, while Fireteam C covered them while they planted the explosives and during their retreat. Following the detonation of the explosives, two of the Skua still carrying bombs would then try to bomb the high-concentration room to maximize damage to the heavy water machinery. Then the men would retreat across the suspension bridge, which the final two Skua would attempt to destroy with their bombs after the men had crossed to slow the German pursuit. The men would commandeer trucks and drive to the coast, where they would seize a small ship and sail with it to Scotland.
Review of Freshman against the Six Principles of Special Operations plus Moral Factors
- Simplicity - In concept, Freshman was quite simple. The men were to land in a glider and infiltrate Vemork.
- Security - Freshman remained a secret from the Germans up until the men from the second glider requested medical attention and the local German commander was informed of their presence.
- Repetition - The conditions in Norway were vastly different than those in the UK. The mountains and winds made it hazardous to land a glider, conditions which had not been emulated in the training of the pilots.
- Surprise - The level of surprise possessed by Gunnerside is that which surprise is almost not applicable; the Germans never knew about the saboteurs until they had already left.
- Speed - The delays for Freshman proved problematic for Grouse, whose men suffered from hunger and harsh weather.
- Purpose - Operation Freshman had a clear, well-defined purpose: to destroy the high-concentration cells at Norsk Hydro’s Vemork plant.
- Moral Factors - The men of Freshman possessed enough courage and boldness to attempt an incredibly dangerous and difficult raid. However, the intellect was lacking within the leadership and planning of the operation, creating the conditions for failure.
Operation Gunnerside: Basement Raid
Following the failure of operation Freshman, Wilson and Tronstad decided to create a small group of Norwegian-native commandos to join with Grouse, and attack Vemork. This new operation, named Operation Gunnerside, would be led by Joachim Rønneberg, with four men of his choice plus Knut Haukelid as his second-in-command, who had been requested by Tronstad.[13] The four men Rønneberg selected were Birger Strømsheim, Fredrik Kayser, Kasper Idland, and Hans Storhaug. After multiple delays, The Gunnerside men parachuted onto the Hardangervidda on February 16, 1943. They met with the Grouse team on February 22. Together, the men decided that they would attempt to scale the ravine and cross the frozen Måna River, which ran below Vemork, to both attack and escape.[14] Then on February 28, 1943, at 2000hrs, the men, led by Helberg, left the hunting cabin they were staying in towards Rjukan Valley, beyond Vemork. The covering team, led by Haukelid, and demolition team, led by Rønneberg, joined-up and at 0045 hrs, March 1, Rønneberg and Kayser entered the building where the heavy water high-concentration cells were through a cable duct, which led to the room next to the high-concentration cells. They surprised the one worker in the room and proceeded to lay the explosives. At 0115 hrs, Rønneberg lit the fuses, the explosives went off, and the men escaped down into the Rjukan Valley and were crossing the Måna River when the sirens at Vemork went off, although no searchlights were turned on. The men then ascended the opposite side of the valley and escaped towards a hut near Lake Langesjå at 0500 hrs, March 1.[15]
By destroying the heavy water cells, it would take approximately one year after being rebuilt for Vemork to independently[16] begin producing high-concentration heavy water. This is because the high-concentration cells at Vemork worked by feeding the heavy water from one cell to the next, mixing it with lower concentration heavy water, which would then be at a higher concentration. This process required the stores of heavy water to be used in order to start production again, severely hampering its efficiency. Gunnerside managed to achieve the destruction of the high-concentration cells without the loss of any life, Norwegian or German. The plan was executed efficiently and swiftly, without any need for the Gunnerside men to fight to get in or out of Vemork. While Rønneberg was laying the explosives, Strømsheim and Idland crashed through the window as they had decided to enter the room by force, which had the potential to compromise their security by alerting the guards of their presence if one happened to notice the light coming from the window.[17] There was one close encounter when Haukelid and Poulsson were guarding the German barracks and a soldier came very near to revealing their hiding spot with his flashlight, but luckily he did not see them and left, preserving the security of the operation.[18] The operation had limited goals and achieved them, leaving me no suggestions for modifications that I believe could improve the effectiveness of the raid.
Review of Gunnerside against the Six Principles of Special Operations plus Moral Factors
- Simplicity - The objectives of operation Gunnerside were limited allowing for a smooth and focused attack. The insider knowledge of the plant was excellent and proved to be highly useful, such as when Rønneberg and Kayser entered the room of the high concentration cells through the cable duct. Gunnerside used innovative methods of attack when they decided to descend and climb the gorge to reach Vemork and Rønneberg and Kayser’s use of the cable duct.
- Security - While the failure of operation Freshman caused an increase in the security measures at Vemork, Gunnerside managed to get in and out of Vemork without alerting the Germans of their presence until they had left.
- Repetition - Rønneberg had practiced laying the explosives on the high-concentration cells for hours on replicas in London.
- Surprise - The level of surprise possessed by Gunnerside is that which surprise is almost not applicable; the Germans never knew about the saboteurs until they had already left.
- Speed - The entire attack, including the infiltration and retreat back to the Hardangervidda, lasted nine hours.[19]
- Purpose - Operation Gunnerside had a clear, well-defined purpose: to destroy the high-concentration cells at Norsk Hydro’s Vemork plant.
- Moral Factors - The men in the raid possessed enough courage and boldness to attempt an incredibly dangerous and difficult raid. The men also had the intellect and perseverance to endure the conditions on the Hardangervidda, and later successfully complete the attack on the heavy water cells.
USAAF Bombing Raid
Following Gunnerside, three options were considered for a second attack on Vemork: (1) interfere with production by internal sabotage, (2) a second attack similar to Gunnerside, and (3) strategic bombing.[20] A daytime precision bombing attack was selected as it was likely to be the most efficient, as with the increased security at Vemork following Gunnerside, it would be difficult to launch a similar operation.[21] The order to attack was sent to USAAF General Ira Eaker, commander of the 8th Air Force. On the morning of November 16, 1943, 388 B-17 Flying Fortresses and B-24 Liberators were bound for Norway, with 178 of them going to Vemork. The bombers were to attack Vemork no earlier than 1145 hrs, as that was when the workers were taking their lunch break. The bombers struck Vemork and its surrounding area with a total of 711 1,000 lb bombs. The bombs tore the bridge in half, destroyed and damaged water pipelines, damaged the power station including the destruction of two generators, and sheared-off the west corner of the hydrogen plant. Several houses were leveled bombs, which caused flying debris and fire to spread the destruction.[22] The bombing raid did stop heavy water production temporarily,[23] however the high-concentration cells remained undamaged, allowing production to resume shortly.[24] The topography of Vemork and its surrounding areas, the limited precision of high-altitude bombing, and the German smoke generators made it unlikely for such a raid to succeed.[25]
Although 21 Norwegians were killed in the bombing, there was no clear intelligence stating that the Germans had stopped pursuing an atomic bomb or were not trying to create other radioactive weapons. The potential costs of allowing the Germans to continue with their atomic research were far greater than those of a bombing raid.[26] By carrying-out the bombing during the workers’ lunch break, the risk of civilian casualties would be decreased, although because the bombers had to loiter to delay the bombing until 1145 hrs, the Germans prepared defenses and managed to kill two bombers.[27] To reduce the civilian casualties, the operation could have been conducted by two squadrons of de Havilland Mosquito bombers, with each aircraft carrying a 1,900 lb General Purpose bomb. These bombs would have had better penetration, and the Mosquitos could have hit their targets with much greater precision, resulting in reduced collateral damage. This would also have allowed for a smaller attacking force, which would mean reduced resource expenditure.
Review of the bombing of Vemork by the USAAF against a subset of the Nine Principles of War
- Mass - The strength of the force attacking Vemork was high; 178 B-17 dedicated to Vemork, although more of the 388 planes going to Norway could have been sent to Vemork.
- Simplicity - The concept of the raid was simple, however, with the constraint of attacking after 1145hrs, the bombers would have to be well-coordinated or sacrifice surprise.
- Surprise - The raid initially held surprise, however when the bombers circled around to delay the bombing it gave the Germans time to try to intercept them.
- Economy of Force - The decision to allocate less than half of the bombers to Vemork reduced the chances of hitting Vemork hard enough to deal lasting damage. Also, the use of heavy bombers was less efficient than dive-bombers for hitting small targets. Dive bombers would have been able to deal more damage to valuable targets while using less resources.
- Purpose - Operation Gunnerside had a clear, well-defined purpose: to destroy the high-concentration cells at Norsk Hydro’s Vemork plant.
Sinking the Ferry D/F Hydro
On December 11, 1943, Dr. Kurt Diebner, a physicist working in the German atomic program, visited Norsk Hydro’s Oslo headquarters. Diebner was told by several officials that Norsk Hydro would not be able to continue production, “as as they could ‘expose the company’s workers to further attack, nor invest another fortune in rebuilding a plant that would be lost in the event of a new air raid.’ Diebner agreed.”[28] He wished to move all of the high-concentration equipment and all stores of heavy water at any concentration, to Germany. There, a new facility would be constructed, giving him access to the heavy water he required, both as a moderator, and a completely different use directly as an explosive. It had already been shown by physicists that when two deuterium atoms, moving at high speeds, collided with each other, it released pulses of energy. Diebner and his team of physicists had begun creating experiments that would use shock waves from shaped charges to squeeze deuterium atoms together, giving Germany a second option for an atomic weapon.[29]
On January 29, 1944 Einar Skinnarland received a message from Tronstad: “It is reported that the heavy-water appliances at Vemork are to be dismantled and transported to Germany. Can you obtain confirmation of this? If it is true, are there any possibilities of preventing the transport? It is a matter of great importance.”[30] Skinnarland visited Vemork engineer Rolf Sørlie, who was a member of the resistance and was able to confirm that Vemork was to be disassembled, and said that the heavy water stocks were to be shipped out first.[31] Skinnarland and Sørlie met with Haukelid, and on February 8, they received orders from Tronstad to destroy as much heavy water as possible, and try to cause minimal harm to civilians. Based on information provided by Sølie, it was determined that they would sink the ferry that would carry the heavy water across Lake Tinnsjø.
On February 10, they were given approval from London to sink the ferry. The men settled on using a time bomb to sink the ferry before it could reach the shore. If they failed to stop the shipment of heavy water from reaching Germany, the Germans would have direct access to heavy water for their atomic research. Haukelid and his men needed to create a hole in the ferry large enough to sink it quickly, leaving the 5,000 gallons of heavy water practically irrecoverable at a depth of 1,300 feet below the surface,[32] while also leaving time for civilians to escape.[33] Sørlie brought along a new recruit he had found, named Knut Lier-Hansen. He was a former Norwegian Army sergeant and worked for the Milorg, the Norwegian resistance, as a weapons instructor, spy, and radioman. Lier-Hansen recruited a man named Olav Hansen to drive them, who after much difficulty, managed to start his car at 0100 hrs, February 20, and then drove Haukelid, Sørlie, and Lier-Hansen the 7¼ miles to within a ¾ mile radius of the ferry dock, at Mael.
The three saboteurs entered the D/F Hydro’s passenger saloon, and were about to open the hatch to the bilge, when they heard a crewman approach, Haukelid and Sørlie hid from him, although Lier-Hansen recognized the man as John Berg from the athletics club. He happened to be sympathetic to the resistance, so Haukelid and Sørlie came out and then Lier-Hansen told him they needed to hide something from the Germans. Berg agreed, and Haukelid and Sørlie entered the bilge, and layed a 12ft tube of plastic explosive, which weighed 19 lbs, in an almost full circle on the hull. Haukelid set the timer for 1045 hrs, wired the electric detonators to the clock circuits, set the alarm-clock hammer in the timer, and connected the detonator caps, completing the time-bomb. At 1045 hrs that morning, the explosives detonated and then the ferry sank. 27 people, including four German guards, survived; however, 22 Norwegians and four guards, did not. Four half-empty drums of heavy water were all of the stocks that surfaced.[34] The losses were high, although given what was at stake, destroying the heavy water had to be the primary goal, with minimizing losses a secondary priority. The plan to sink the heavy water and its execution was designed to minimize civilian losses while completing the mission, and the execution of the plan went without any trouble.[35]
Review of the Sinking of the D/F Hydro against the Six Principles of Special Operations plus Moral Factors
- Simplicity - The objectives were limited and there was sufficient intelligence about the timing of the ferry. The innovation on this attack was excellent, the bomb timer which proved vital to the mission was made by Ditlev Diseth, the owner of a clock repair shop. The alarm clock timer was precise enough for a delay of multiple hours, unlike a fuse.
- Security - The security of the commandos planting the bomb was adequate, however it was nearly compromised when they were discovered by John Berg, although luckily he was a resistance sympathizer.
- Repetition - Haukelid had practiced using explosives in training, however, the alarm clock timer was a new innovation. The men had not practiced the full attack, however, the attack did prove to be successful.
- Surprise - The bomb was completely unknown until it went-off, successfully sinking nearly all of the heavy water stocks.
- Speed - The planting of the bomb was not particularly quick, however the commandos’ presence was known and permitted.
- Purpose - The purpose of the attack was clear: destroy the stocks of heavy water from Vemork.
- Moral Factors - Although they had to place civilians in danger in order to sink the heavy water in the Hydro, the group persevered and set-up the attack with courage, boldness, and intellect.
“SOE’s achievements in successfully destroying the heavy water production facilities at the Norsk Hydro Plant in Vemork established the organisation’s reputation for the rest of the war.”[36] Diebner believed that the attack on Vemork was the main reason why the German atomic program did not achieve the necessary conditions to sustain a reaction. In May, 1945, a facility with almost a sufficient quantity of heavy water to develop an atomic bomb was discovered in Bavaria. Without precise knowledge of whether the Germans would have been able to create an atomic bomb before the Allies, the attacks launched by SOE provided insurance against the event that the Germans were on the course to develop an atomic bomb before the Allies.[37]
Sources
- Bascomb, Neal. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. New York: Arthur A. Levine Books, 2016.
- Greentree, David. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. Oxford: Osprey Publishing, 2018.
- Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986.
- “The Special Operations Executive 1940 - 46.” British Broadcasting Company. Published February 17, 2011. Accessed January 18, 2019. http://www.bbc.co.uk/history/worldwars/wwtwo/soe_01.shtml.
- “The Winter Fortress.” C-SPAN. Published May 11, 2016. https://www.c-span.org/video/?409379-1/neal-bascomb-discusses-the-winter-fortress.
- “Weather statistics for: Hardangervidda nasjonalpark, Eidfjord (Hordaland).” Norwegian Meteorological Institute. Accessed January 18, 2019. https://www.yr.no/place/Norway/Hordaland/Eidfjord/Hardangervidda_nasjonalpark/statistics.html.
Footnotes
[1] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 21-22.
[2] Ibid., 35-38.
[3] Ibid., 54-55.
[4] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 46-47.
[5] “Weather statistics for: Hardangervidda nasjonalpark, Eidfjord (Hordaland),” Norwegian Meteorological Institute, accessed January 18, 2019, https://www.yr.no/place/Norway/Hordaland/Eidfjord/Hardangervidda_nasjonalpark/statistics.html.
[6] Ibid.
[7] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 81.
[8] Ibid., 67-106.
[9] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p.16, 46.
[10] Ibid., p. 17.
[11] Ibid, p. 23.
[12] “The Winter Fortress,” C-SPAN, published May 11, 2016, https://www.c-span.org/video/?409379-1/neal-bascomb-discusses-the-winter-fortress.
[13] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 106-112.
[14] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 35-47.
[15] Ibid., 46-47.
[16] Richard Rhodes, The Making of the Atomic Bomb. (New York: Simon & Schuster, 1986), p. 457
[17] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 166-167.
[18] Ibid., 168-169.
[19] Ibid., 166.
[20] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 205.
[21] Ibid.
[22] Ibid., 205-213.
[23] Ibid, 211-213.
[24] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 64-65.
[25] Ibid.
[26] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 213-215.
[27] Ibid., 210.
[28] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 218.
[29] Ibid.
[30] Ibid.
[31] Sabotage
[32] Ibid., 229.
[33] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 68-69.
[34] Ibid., 73.
[35] Neal Bascomb. Sabotage: The Mission to Destroy Hitler’s Atomic Bomb. (New York: Arthur A. Levine Books, 2016), p. 233-242.
[36] David Greentree. Heroes of Telemark: Sabotaging Hitler’s Atomic Bomb, Norway 1942-44. (Oxford: Osprey Publishing, 2018), p. 75.
[37] Ibid., 77.