Operation Freshman Operation Freshman was the codename given to a British airborne operation conducted in November 1942 during World War II . It was the first British airborne operation conducted using gliders , and its target was the Vemork " Norsk Hydro " chemical plant in Telemark county , Norway which produced heavy water for Nazi Germany . By 1942 the German atomic weapons programme had come close to being able to develop a nuclear reactor , but in order for the reactor to function it would require a great deal of heavy water . The source of the heavy water was the Norsk Hydro plant , which had been occupied in 1940 ; when the British government learned of the German nuclear developments , it was decided that a raid would be launched to destroy the plant and deny the Germans the heavy water required to develop a nuclear weapon . Several tactics were discussed and discarded as impractical , and it was finally decided that a small airborne force composed of sapper s from the Royal Engineer units attached to 1st Airborne Division would land by glider a short distance from the plant , demolish it with explosives and then escape over the Norwegian border into Sweden . After a period of extensive training , the airborne force took off in two aircraft – glider combinations on the night of 19 November 1942 . Both managed to reach the Norwegian coast , but neither was able to reach their objective . The first pair suffered from navigational difficulties and severe weather , which resulted in the tow rope snapping and the first glider crash – landing , with its towing aircraft returning to base ; eight airborne troops were killed outright , four were severely injured and five unhurt , with the survivors captured shortly after the crash . The second pair fared even worse , with both aircraft and glider crashing into a mountain for unknown reasons ; the aircrew and a number of airborne troops were killed outright , and those who survived were taken prisoner . None survived for very long , either being poisoned or executed as a result of Adolf Hitler ' s Commando Order , which stated all Commando personnel were to be immediately executed upon capture . At the end of the war , a number of Wehrmacht personnel were tried and condemned to death for their part in the executions . Background . The German government began development of an atomic weapons programme in April 1939 when two scientists , Irene and Frédéric Joliot - Curie , declared in an issue of the scientific journal " Nature " that atomic fission was possible and could produce immense amounts of power . The Joliot - Curies argued that not only did it have possibilities as a power source , it might also be used to create an extremely powerful weapon . By September 1941 the German scientists assigned to the programme had determined how a nuclear reactor could be developed ; this required significant quantities of heavy water to act as a neutron moderator to encase the uranium which would be used to provide the material for a nuclear weapon . Heavy water was extremely scarce and difficult to produce , and Germany only possessed a small amount which had been produced in laboratories . Norway possessed a large amount which was produced by the Vemork " Norsk Hydro " chemical plant near the village of Rjukan , but the Norwegian government would not sell more than three gallons of heavy water a month , becoming suspicious of the sudden increase in demand for the water by the German government . When Norway was invaded and occupied by Germany in April 1940 , however , this obstruction ended ; the Vemork plant was captured and began producing heavy water for the German atomic weapons programme . Production of heavy water was slowed initially due to the effects of the fighting in Norway and a drought in the area , which led to a lack of water to provide hydroelectric power for the plant . However , once the weather improved and snow began to melt , providing enough water to create sufficient hydroelectric power , production continued . By mid - 1942 it had come to the attention of the British government that the plant had begun to produce large quantities of heavy water and was stockpiling it for later use . The decision was therefore taken that the plant and the stockpiles of heavy water would have to be destroyed in order to impede the German programme . A number of methods for destroying the plant were considered . The first was a mass raid by Royal Air Force ( RAF ) bombers , but this was rejected due to the difficulty in locating the plant during night bombing , the principal bombing tactic used by the RAF at the time , and the heavy casualties that would be inflicted on the local Norwegian population during a night raid . An attack by Norwegian saboteurs was also ruled out , as was landing troops by PBY Catalina flying boat on Lake Møsvatn , from the target , the latter due to the steepness of the surrounding mountain slopes and the inability of flying boats to land on the frozen water . It was decided that a raid by glider - borne airborne troops would have the greatest chance of success . The area around the plant would be difficult to land on , but a possible landing site for gliders was located near the Møsvatn dam , although it would require considerable skill on the part of the glider pilots in order to land safely . Preparations . Operation Grouse . In March 1942 SOE had recruited Einar Skinnarland , a Norwegian engineer who worked at the Møsvatn dam . Skinnarland had successfully sailed to Britain and was parachuted back to Telemark after ten days of intensive training . Having several contacts within Vemork he was able to roughly identify the disposition of German troops and other defences . Additionally SOE decided to send an advance party of Norwegian agents into Telemark , and began intensively training a four - man team over the summer . The party , code - named Operation Grouse , was led by Jens - Anton Poulsson and also included Knut Haugland , Claus Helberg and Arne Kjelstrup . The Norwegians , all people local to the area with exceptional outdoors skills , underwent extra outdoor training in Scotland as well as learning the skills necessary to operate in occupied territory ; including sabotage , radio transmitting and " irregular warfare " . The Grouse team were ready to be inserted by October . Several flights were made but aborted due to bad weather , before the team finally dropped on 18 October . The team landed at Fjarifet on the Hardangervidda ( a large wilderness avoided by the German forces ) and spent the next 15 days trekking towards Møsvatn , where they made contact with Skinnarland ' s brother , Torstein . Once they had established contact with London the party began making preparations for the arrival of the British commandos . A suitable glider landing site was chosen south west of Møsvatn dam and the team reconnoitred the area to help Combined Operations decide the best way to attack the plant . German defences . The geography of the area around the village and the plant meant that attacking the plant and destroying the existing stocks of heavy water would be extremely difficult . Both were situated in a deep valley which possessed thickly – forested sides that rose almost vertically from a narrow river – bed , and which was overlooked by Gaustatoppen , a mountain approximately high ; the plant itself had been built on a broad rock shelf above the river bed . Einar Skinnarland had observed the German defences over the summer and passed the information back to SOE . Later reconnaissance by Torstein Skinnerland and the Grouse team was also transmitted to London in the weeks leading up to the operation . In early October Generaloberst Nikolaus von Falkenhorst , the commander in chief of the German forces in Norway , had personally visited the plant . While there he warned the local garrison that he believed the plant was a likely target for British commando raids , but crucially he did not have the resources to increase the manpower there . Although Einar Skinnarland had observed a garrison of some 100 men in the village of Rjukan , 20 at the dam and about 55 near the main plant during the summer , by October this had been reduced to about 12 at the plant , 12 at the dam and approximately 40 in Rjukan . Most of the men were elderly or infirm Austrians under the command of an elderly captain , although well trained German regulars periodically passed through Telemark . Skinnarland also believed that Gestapo agents were in the area . The Germans had erected three iron hawser s across the valley to prevent low flying bombing raids but on the ground most of their defences were positioned to prevent an assault from the ridge above the plant , the direction from which they believed an attack was most likely . Minefields and booby traps predominantly protected this side of the plant , but there were also searchlights on the roof and a machine gun nest near the entrance . A single bridge crossed the steep gorge in front of the plant , but was normally only protected by two guards . However , there were some 300 , 000 German troops in Norway at this time and reinforcements could quickly be called into the area , which would complicate the commandos ' escape to the Swedish border . Planning . The Headquarters staff of Combined Operations at the War Office was tasked with devising a plan for the glider - borne assault on the plant , as it had been with previous airborne and commando operations , such as Operation Biting . This would be the first British airborne operation ever to use gliders ; all previous operations had been conducted solely with parachutists . The staff decided that although gliders would be the most suitable for the operation due to the heavy loads to be carried by the airborne troops , and the possibility that they could be widely dispersed if they were dropped by parachute , the airborne troops would still be trained for a possible parachute insertion if the landing zone for the gliders was found to be unsuitable . Because of the complicated and technical nature of the operation , which would see the plant rigged with explosives and then detonated , it was believed that a minimum of twelve to sixteen men would be required , and that they would all have to be skilled engineers . The important nature of the operation also led to the force being doubled in order to duplicate it , to ensure that even if half of the force were killed , the survivors would have the necessary skills to complete the operation . The selected troops were volunteer parachutists chosen from the sapper s of 9th Field Company ( Airborne ) Royal Engineers and 261st Field Park Company ( Airborne ) Royal Engineers attached to 1st Airborne Division , because the only parachute - trained Royal Engineers unit in existence at the time , 1st Parachute Squadron Royal Engineers , was already deployed in North Africa with 1st Parachute Brigade . Both of the duplicated units that were to participate in the operation were to be commanded by officers from the Royal Engineers ; the first by Lieutenant A . C . Allen and the second by Second - Lieutenant M . D . Green , who was later replaced by Lieutenant D . A . Methven when he was injured during a training accident three days before the operation was to begin . The Royal Air Force unit selected to transport the sappers was 38 Wing , which was commanded by Group Captain T . B . Cooper ; it was provided with a special allotment of three Handley Page Halifax heavy bomber s for the operation , which were the only British aircraft in existence at the time which were capable of towing Horsa gliders the distance required and then returning to their base . The SOE agents selected a landing zone for the sappers , which was approximately from the Norsk Hydro plant and could not be observed by German patrols . The plan for the operation called for the sappers to land in the two gliders at the landing zone , guided in by the SOE agents equipped with Eureka radio beacons . Once they had successfully landed , the sappers would be escorted to the plant by the SOE agents , demolish the plant and its stocks of heavy water , and then cross the Norwegian border into neutral Sweden . Combined Operations initially suggested the men should fight their way to the Swedish border , but MI9 believed their chances of survival were better if they attempted to disguise themselves at Norwegians and travel in pairs . In order to facilitate their escape the men were provided with civilian clothes ( to be worn after the operation ) , simple Norwegian phrases ( in the hope no German they encountered would speak Norwegian anyway ) and escape sets containing money and maps . They were also ordered to shave any moustaches and grow their hair long in order to blend in with Norwegian men . Training . Training began in early October in Wales and was designed to be extremely arduous , not only to ensure that those who took part would be at the peak of their physical and mental fitness , but also to eliminate any individuals unable to cope with the long marches and difficult terrain that would be encountered during the operation . When this portion of the training had been completed , the sappers were then transferred to the area around Fort William in Scotland , where they were familiarized with a hydroelectric plant similar in design to the one in Norway , and received training on the most efficient way to plant explosives in the Norsk Hydro plant to cause maximum damage . Training also took place at Port Sunlight , where they were shown how to destroy large condensers of the kind found in the plant . The sappers were given detailed briefings on the plant and the surrounding area , and were trained on large models and mock - ups of the buildings that the plant was composed of , all based on information provided by the SOE agents who had arrived earlier in the month . Because the operation was considered to be extremely important , and its results vital to the Allied war effort , security efforts were extremely thorough . A cover story was provided for the sappers as they conducted their training ; a rumour was spread that they were training to compete against a company of American engineers in a fictional ' Washington Cup ' athletic event , which involved a long route march to be completed either by glider or parachute , followed by a complex demolition task and finally a demanding endurance test . The departure airfield was also sealed off to civilians and non - essential military personnel , and all mail and telephone calls were censored . Operation . After their training had been completed , on 17 November the sappers were transported to an RAF airfield at Skitten in Scotland , with the operation scheduled to commence two days later . On the evening of 19 November , Group Captain Cooper , with the aid of a Norwegian meteorologist and regular reports from the SOE agents stationed near the landing zone , decided that although the weather was not perfect , it would be best to launch the operation that night ; Cooper believed that if it were delayed , the weather might deteriorate on subsequent days and prevent the operation from being conducted entirely . The first aircraft – glider combination took off from the airfield at 17 : 50 , with the second following at 18 : 10 ; after circling the airfield several times the two combinations headed out across the North Sea towards their objective . The first combination . The first combination flew through poor weather conditions and managed to reach Norway and fly towards its objective ; however during the flight over Norway the Rebecca receiver , which was supposed to pick up the transponder signal from the Eureka beacons being used by the Norwegian SOE agents , developed a mechanical problem and was unable to pick up the signal . This left the aircrew with only map - reading available to locate the landing zone , but the poor weather made this almost impossible . On a second attempt to find the correct area , the combination flew into thick clouds approximately northwest of Rjukan , and ice began to form on both aircraft and glider , as well as the towing rope connecting the two . At this point the combination began to lose altitude , and the towing rope snapped , setting the glider free ; low on fuel , the aircraft was forced to turn back after signaling to Skitten at 23 : 55 that it had released the glider , and only just succeeded in landing back in Britain . Shortly after releasing the glider , the aircraft broadcast a second message , " Glider in sea " , indicating the air crew ' s belief that the glider had crashed . The Royal Navy was asked to begin a search - and - rescue mission , but had no ships in the area ; an aerial search of the area was instead conducted , but did not find the glider . In fact the glider did not land in the sea , but crash - landed in an area called Fyljesdal , overlooking Lysefjord . Of the seventeen men on board , eight were killed outright , four were severely injured and five unhurt . Thorvald Fylgjedalen , a local farmer , found some of the injured soldiers from the glider , but knew no English , and was unable to communicate with them . Nonetheless , Fylgjedalen and his neighbor Jonas Haaheller decided that they would assist the wounded soldiers , and did not contact the German authorities . After contacting more of the local residents , the soldiers asked for their assistance in escaping to Sweden , but Haaheller and others convinced them that this would be impossible , as it would involve traveling across the entirety of Norway . Thus , the Norwegians sheltered and gave medical attention to the injured soldiers , but did not allow any of them to leave . The Norwegians also burned all of the maps and documents from the glider crash before the Germans could arrive , and managed to keep the entire operation secret for almost twenty - four hours . German soldiers , including troops from both the Waffen SS and the Army , arrived the next afternoon on two boats from a nearby camp . They quickly took the British soldiers prisoner , and departed with them on the boats . Despite the grave injuries suffered by some of the soldiers , they were still forced to walk under their own power and ride in the unsheltered boats in the cold . The dead soldiers were dumped in a shallow grave . The second combination . The second combination managed to reach the coast of Norway , but fared even worse than the first combination ; for unknown reasons the tow aircraft released the glider at a great height and then crashed into a mountain at Hestadfjell . All of the aircrew were killed instantly . Workmen in the area heard the plane pass overhead shortly before crashing and alerted the German authorities , who arrived quickly . Finding no survivors , the Germans threw the bodies of the aircrew into a nearby bog and left the area . Released just before the tow aircraft crashed , the second glider spiralled out of control and crash - landed in the mountains between Helleland and Bjerkreim . Seven of the men were killed instantly , and the rest were injured to varying degrees . The survivors were unwilling to leave the seriously wounded and two of the British soldiers left the crash site to search for help . After searching for some time , they arrived in the town of Helleland about from where they had crashed , and made contact with one of the local residents , Trond Hovland . The soldiers told Hovland about their injured comrades , and asked if he could help them find a doctor . Hovland agreed to help , but informed them that the nearest doctor lived away , in the town of Egersund . In order to contact him , Hovland would have to use the telephone system , controlled by the German authorities , which would alert them to the presence of the soldiers . Believing that there was no alternative , the soldiers agreed to contact the Germans , expecting that they would be taken as prisoners of war . A party from the Norwegian Labour Service arrived at the crash site shortly afterwards and helped tend to the injured soldiers who burned all of their sensitive documents and materials . A German party arrived about twenty minutes later and the British then submitted without a struggle . After their arrest , the prisoners were taken to the German camp at Slettebo near Egersund . Aftermath . The Allies were unaware of the fate of the operation until they intercepted a German communiqué stating that two gliders and one aircraft had been forced down , and the crews engaged and annihilated . On 11 December they received a message from an SOE agent explaining that the second gliders occupants had all been shot . Many of the details about the fate of the two glider combinations were only discovered after the war had ended . None of the soldiers or aircrew who survived the crashes remained alive for very long . Of the soldiers from the first glider , three of the four injured men were tortured by the Gestapo and later killed by a doctor who injected air into their bloodstreams . The fourth injured man was shot in the back of the head the next day . All four bodies were dumped at sea . The five uninjured men were held at Grini concentration camp until 18 January 1943 , when they were taken to nearby woods , blindfolded and executed by the Gestapo . The German Wehrmacht and the Gestapo argued over the fate of the prisoners from the second glider . The Wehrmacht believed they should be treated in accordance with the Geneva Convention , but in the end the survivors were interrogated and executed within a few hours of their capture at the German barracks at Bekkebo . They were taken into nearby woods and shot one by one , each being forced to listen to the man before him being executed . Their bodies were stripped and thrown into an unmarked grave . All of the executions were conducted in accordance with the Commando Order issued by Adolf Hitler in October 1942 , which stated that all Commando troops were to be killed immediately upon capture . The local Norwegian population were unable to prevent the prisoners being executed , but tended the graves of the dead until the end of the war . Although the Allied soldiers believed that they had burnt all of their maps , one from the second glider was missed . When the Germans found it they were able to identify the Vemork plant as the target and increased their defence accordingly . German reprisals started instantly and 200 armed Gestapo agents swept into Rjukan where they arrested 21 Norwegians for questioning , but the members of " Operation Grouse " slipped away into the wilderness of Hardangervidda . They later contributed to the successful Operation Gunnerside in February 1943 , when a small team of Norwegian SOE agents were parachuted into the area and demolished much of the Vemork heavy water plant . The plant did eventually resume operation , but further bombing raids ensured it produced little heavy water for the German atomic weapons programme . Although the operation had been a failure , it demonstrated the range , flexibility and possibilities of airborne forces and glider operations , and also highlighted equipment failures that were rectified for later operations . This included developing a new version of the Rebecca - Eureka homing device system , the Mk II , which was ready by 1943 and proved to be very successful when used in later airborne operations ; during Operation Market Garden and Operation Varsity , aircraft that used the system reported a 95 % success rate . When 1st Airborne Division arrived in Norway in May 1945 , they were informed of the fate of the prisoners , and cooperated with the Norwegian government to have the fallen men buried with full military honours . The five from the first glider were re - interred at the Commonwealth War Graves plot at Vestre Gravlund near Oslo . The second glider ' s occupants were reburied at Eiganes churchyard in Stavanger and the Halifax aircrew were reburied at Helleland . The head of the Gestapo in Oslo , who had signed the order for the prisoners ' executions , committed suicide several days prior to 1st Airborne Division ' s arrival in May 1945 , but several Wehrmacht personnel implicated in the decision to execute the prisoners were put on trial and found guilty ; one was shot and another hanged , whilst a senior Non - Commissioned Officer who had shot a prisoner in the back of the head was extradited to the Soviet Union for alleged abuse conducted against Soviet prisoners . Furthermore , the commander of the German forces in Norway – Generaloberst Nikolaus von Falkenhorst – was also found guilty of two of the Freshman deaths during his war crimes trial .