EARLY in 1942, Thomas Sneum, one of the first two Danes who escaped directly to Britain, was one of the first two Allied agents to return by parachute to Denmark. With them they brought a portable wireless transmitter, and in Copenhagen they met Arne Duus-Hansen, an engineer for the radio firm of Bang og Olufsen, who helped them broadcast their first message to England.
After several months, however, Sneum’s presence in Denmark was detected by the Germans, and he fled on foot across the frozen Sound to Sweden in early 1943. Duus-Hansen then helped the next Allied agent who parachuted into Denmark to make radio contact with S.O.E.
Like Sneum, this agent had brought the same sort of broad-casting gear that had been sent to underground organizations in other German-occupied countries. This equipment was entirely unsuited to Denmark’s needs because it was too large to be transported without arousing suspicion, and it operated only on alternating current, although at that time nearly all of Copenhagen was supplied with direct current. And worse, the transmitter’s valves were mostly of types that could not be replaced in Denmark.
Several more parachutists soon arrived, always with the same sort of cumbersome, impractical transmitters, and what radio contact they could establish with Britain was slow and unreliable. The Danish Resistance, now growing rapidly, needed better radio connections, yet Britain was unable to provide either properly qualified radio operators or the sort of equipment suitable for the job. In an attempt to solve the problems, Duus-Hansen was called to Stockholm to meet representatives from S.O.E. ‘Why not,’ the Dane suggested, ‘let us train our own radio operators?’
A completely unworkable idea, the representatives said, because the job had to be done by men trained in Britain, men who knew the British procedure, men the British were sure would be reliable.
‘Nonsense !’ Duus-Hansen said. ‘Any man who can’t tap out and receive, say, a hundred and twenty letters a minute is no good for this job, and you don’t have any Danes you can train as operators in a few months. This job is dangerous enough for professionals. You send us amateurs!’ He then went on to explain the inadequacies of the broadcasting sets. The S.O.E. representatives replied that they were sorry, but after all, the needs of the Danish Resistance did not rate high priority.
Why not, Duus-Hansen suggested, let the Danes try to solve their own radio problems? He personally would undertake to recruit professional operators in Denmark, and if the British would send him frequency crystals, he would find a way to provide transmitters suitable to Danish needs.
The British were frankly sceptical, but eventually London decided to give the Danes a chance, and crystals were dispatched to Copenhagen. Within a few weeks Duus-Hansen produced one of the most remarkable pieces of gadgetry used by any Resistance organization. The wireless set he built in occupied Copenhagen was smaller than a London telephone directory, worked on both alternating and direct current, used valves that could be replaced with those in almost any Danish home wireless, transmitted on all the frequencies assigned to the Danish Resistance, weighed only three pounds, and had twice the power output of the British-built transmitters. Later, one of these sets was sent to England to be studied for possible reproduction for use in other occupied countries.
Duus-Hansen and the British agreed that, ideally, each radio operator should have three transmitters at his disposal, and a man named Ruhe agreed to make parts for about sixty in his Copenhagen factory. A post and telegraph engineer named Hasselback then studied the set with Duus-Hansen and made several suggestions, and among other things, reduced its dimensions even more. In the occupied city a clandestine assembly line began to put together the tiny sets at night.
Duus-Hansen had little trouble recruiting the promised operators, and these professionals—only one, Jens Holback, was a radio amateur—established regular powerful wireless contact directly between Britain and the Resistance cells throughout Denmark. Satisfied with the service, the British no longer bothered to train Danes to send into the country as radio operators.
Broadcasting to England was in many ways one of the most dangerous jobs in the Danish Resistance, for the Germans moved efficient direction-finder units into the country, and the Danish operators found themselves the quarry in a constant cat-and-mouse game. At least four guards were stationed in streets near where transmissions were made, to give a warning if direction-finder vans approached. Both BOPA and Holger Danske offered to destroy the vans, but the radio men thought this was a bad idea because they could be easily replaced, and, also, it was felt that the Germans in the vans would be less bothersome if they were not forced to carry on a form of open warfare. Moving from one place to another, often sending a transmitter ahead the day before a broadcast, leaving it after the transmission had ended, and then returning for it later, the operators did their jobs well, sending from country farms, from houses in busy city streets, and often from hospitals.
Direction-finders could not be enclosed in steel-bodied vehicles, but the Germans, disguising the vehicles as canvas-covered delivery vans, made the mistake of using petrol-driven vehicles at a time when all Danish transport was powered by wood-fired gas generators, petrol being unavailable to civilians. Some of the radio operators’ guards learned to spot the vans nearly a mile away.
When Fischer-Holst, one of the operators, had difficulty stringing up an outdoor antenna one day, he decided to experiment with an indoor aerial. To his surprise, the British responded that his message was coming in particularly strongly. From then on the broadcasters hung their aerials indoors, thus making detection less likely.
All of the operators had many exciting experiences. Once a Jutland radio man was to transmit from a hotel where, unknown to him, the Gestapo occupied some rooms. After he had gone to bed that night there was a shattering explosion. A sabotage charge had sent the whole building up in flames. In his pyjamas, the broadcaster climbed toward the top of the hotel, the precious radio transmitter in an attaché case in his hand. From the rooftop he saw Danish firemen raising rescue ladders, and he let them take him and his attaché case down the ladder. Pretending to be dazed, he then walked straight through the German police cordon around the hotel.
During one transmission from a Hellerup villa, Fischer-Holst was warned that a director-finder crew was parked outside the house. After patiently finishing his broadcast, he stepped out of the front door. A petrol-driven van with a canvas enclosed body was at the kerb. Calmly the operator paused, plucked a rose from a bush growing at the doorway, slipped the flower into his lapel, and strolled past the Germans.
Fischer-Holst’s closest call came when he broadcast from the Herlufsholm Grammar School in a manor house in Nætved, a village fifty miles south of Copenhagen. He had to tap out his message from a classroom full of wide-eyed Danish school-boys. Just as he was signing off, one of his guards came to warn him that a direction-finder unit was near by, and that the school swarmed with Gestapo men. Not stopping to get rid of the transmitter, Fischer-Holst was led through the north wing of the building to the chapel. He could hear German voices outside.
The Herlufsholm Chapel, a thirteenth-century building, is the final resting place of many famous Danes. Hiding behind the casket of one of Denmark’s most famous admirals, the little radio operator had an idea. He slid aside the stone casket lid and placed his radio transmitter inside. Closing the sarco phagus again, he escaped through a side door. Minutes later the Germans entered the chapel, and certain that the Resistance operator was still in the building, searched it methodically, but they never thought of opening the caskets. Fischer-Holst, meanwhile, was able to get far away from the school, and several days later his guards returned to retrieve the broad casting set.
The danger to the radio operators remained great as the demand for their services increased. The airwaves between Denmark and England were crowded, and the operators could be asked to take no greater risks by transmitting more frequent messages. Sent to Sweden to discuss with the British the problems of more broadcasts, Duus-Hansen received the sug gestion that the Danes try using high-speed sending equipment. Of course, the British said, they doubted that he would be successful. Mechanical devices did exist that could be used to send speedy messages, but the British did not see how such equipment could be adapted to clandestine broadcasting. They admitted frankly that none could be spared for Denmark. Duus-Hansen, however, had some ideas. ‘You set up your receivers,’ he told his British friends, ‘and I believe our people can do the rest.’
In a few days the Danes had solved the problem. Stealing equipment from a Frederiksberg officers’ training school, the Danish Resistance managed to be on the air with high-speed transmissions four days after the British conferred with DuusHansen. The messages were perforated on paper tapes which were run at speed through a broadcasting transmitter, and the signal, sounding almost like a continuous blip, was received and recorded on ordinary gramophone discs. The records needed only to be played back slowly to transcribe the mes sages. As many as eight hundred letters a minute were sent this way. The messages were transmitted in a numerical sequence, and as long as no numbers were missing, the British did not bother even to send confirmation messages. Soon the Danes built tiny high-speed players, so small that one of these would fit inside an attaché case with the broadcasting sets.
As the German direction-finder vans became more of a nuisance to those operators who still had to transmit at normal speeds, Duus-Hansen was flown from Stockholm to London to discuss other possible radio techniques. In the face of German vigilance, he suggested; why not establish a Danish radio relay station in Sweden?
The British said that, officially, they could not give their permission to have Sweden’s neutrality violated in this way— but such a system would nevertheless be welcome. ‘Mind you, one of the British officers cautioned, ‘we must forbid such action.’
The American Embassy in Stockholm agreed to establish a consular annexe in Malmø into which they would move one of three American wire recorders then in Europe, and into which Duus-Hansen would move some of his Danish-built equipment. He then assembled a relay station in the top storey of the building, and soon high-speed transmissions began on the Denmark-Sweden-Britain hook-up on ultra-high-frequency. Because the Germans were sure no secret radio would ever broadcast on such a wavelength, this signal was thought to be commercial and was not even monitored.
Some months earlier, a Mrs. Bonnesen, Duus-Hansen’s code girl in Copenhagen, had been captured by the Germans and taken to Shell House for interrogation. Left alone for a few minutes, she had succeeded in walking out of the building and strolling past the guards, through Copenhagen, and to DuusHansen’s headquarters, the only person ever to make such an easy escape from the Copenhagen Gestapo offices. In Sweden she had been appointed an American consular assistant. In this capacity she would be useful to the Resistance. A second Danish radio station was erected in Sweden, this time in the U.S. consulate in Helsingborg. Operated at first by an American and later by Mrs. Bonnesen, it received not Morse but voice messages, and it dispatched relatively low priority communications such as Informatíon bulletins. These would then be sent out of Sweden through diplomatic channels. Later Mrs. Bonnesen went back to Malmø to work the relay station there, and she also received British and American airmen who had been slipped out of Denmark by the Resistance.
When the Germans began having supply problems toward the end of the war, the Danes decided to attack the direction-finder vans. Fischer-Holst was to act as decoy and Holger Danske saboteurs would blow up the Nazi vehicle when it drew near. However, the saboteurs, seeing Fischer-Holst’s guards lingering near by, thought they were part of the locator’s crew. By the time the guards had explained them selves, the German van was so near that all the men—guards and saboteurs alike—had to rush to warn the operator to stop his transmission. Luckily, none of the Danes was apprehended.
Another raid on a direction-finder van was slightly more successful. The van was fired on by Resistance agents and several Germans were killed, but after a short battle the van withdrew on bullet-flattened tyres. This attack so worried the Germans that afterwards they always skirted no more closely than half a mile from the transmitting places.
Early in 1945 the Danes found what was probably the final solution to their radio problem. They erected a directional sending antenna of the south coast of Sealand, opposite Malmø. Broadcasting on ultra-high-frequency, and using special reflectors that allowed broadcasts to be aimed on a slim five-degree beam, they worked undetected. From the time this system was established until the end of the war, the main purpose of other broadcasts on the conventional transmitters was to divert the Germans from this service.
Of about twenty Danish operators, only four or five were caught and killed, and these because they were lax in obeying security rules. If they were captured, the operators had been told to broadcast for the Germans, making sure to omit the coded recognition signal in the ‘preamble’ of their messages. Resistance radio codes were of a type that could not be broken—even if the Germans captured the charts and had the code system explained to them. One Danish operator was taken by the Gestapo and forced to send a coded message to England saying that he had forgotten the name of the Jutland sabotage leader and also the man in charge of Resistance finance. This was much too obvious a ruse, and the German message was bound to be recognized as false even had the absence of the recognition signal not alerted the British. In any case, other Resistance radio people had already signalled that one of their number had been captured.
Never badly compromised, Danish Resistance radio was more efficient than any other underground broadcasting—and it was the only clandestine broadcasting worked entirely from within an occupied country.