Operation Carthage

Shortly before noon on 21 March 1945 eighteen twin-engined de Havilland Mosquito bombers swept over the rooftops of Copenhagen. They flew so low that they passed between chimneys and masts. Their target was the Shellhus – the Shell company’s office building in the city centre, which since 1944 had served as the headquarters of the Gestapo in Denmark. It was here that the German Security Police kept its files on the Danish underground, here that it interrogated and tortured those it arrested, and on the top floor it held prisoners as a human shield against air attack.

Operation Carthage, carried out by the RAF at the request of the Danish resistance, achieved its aim: the building burned, the archives were destroyed and eighteen prisoners managed to escape. But one of the first aircraft struck a floodlight mast and crashed beside a Catholic school in the Frederiksberg district. Some of the crews that followed mistook the smoke from the wreck for the burning target and bombed the school. Eighty-six children and about twenty adults were killed. A raid intended to save Danes became one of the greatest tragedies of occupied Denmark.

The Gestapo in Denmark

Denmark, occupied by the Germans on 9 April 1940, kept its own government, parliament, police and king, Christian X, during the first years of the occupation. This “model protectorate” collapsed in the summer of 1943: a wave of strikes and sabotage led the Germans to declare a state of emergency on 29 August, dismiss the government and disarm the Danish army. A few weeks later the Danes saved most of their Jews, ferrying them across the Øresund to Sweden. The resistance, coordinated by the Danish Freedom Council (Danmarks Frihedsråd), grew stronger, and sabotage groups working with the British Special Operations Executive (SOE) destroyed railway lines and factories producing for Germany.

The occupiers answered with mounting terror. The Reich plenipotentiary Werner Best, together with the SS, the Security Police and the Sicherheitsdienst, all answerable to Himmler, built up the machinery of repression; on 19 September 1944 the Germans disbanded the Danish police and deported nearly two thousand policemen to camps in Germany. Danish collaborationist units were active, among them the HIPO, an auxiliary police force formed by the Germans from Danes, and sabotage and assassinations by the underground were met with “counter-terror”: reprisal killings and the blowing-up of public buildings. The Gestapo took over the Shellhus on Kampmannsgade, by the lakes in central Copenhagen, and assembled there card indexes covering the entire resistance. In the winter of 1944–1945 a wave of arrests struck the underground’s leadership; among those held in the building were members of the Freedom Council and officers of Danish military intelligence.

The underground’s request

The Danish underground had long been asking the British to bomb the Shellhus. It wanted two things: the destruction of the card indexes from which the Gestapo drew its knowledge of one person and network after another, and – if at all possible – the release of the prisoners. For a long time the RAF refused. The building stood among the dense buildings of the city centre, next to the Technological Institute, where some 600 people were present every day; a precise hit required an attack at rooftop height, and any mistake threatened civilian casualties. The requests were renewed ever more insistently, however, especially after the arrests of resistance leaders at the turn of 1944 and 1945. In the end the RAF agreed.

The British already had experience of such missions. In February 1944 Mosquitos had breached the walls of Amiens prison (Operation Jericho), and on 31 October 1944 they had destroyed the Gestapo headquarters in the buildings of Aarhus University with almost no harm to local residents. The Copenhagen raid was more difficult, however: the target lay in the very heart of the capital, which was defended by anti-aircraft artillery, including the guns of the cruiser Nürnberg lying in the harbour. For several weeks the planners of No. 2 Group RAF prepared the attack; a model of the building and the surrounding blocks was built for the crews.

The raid

On the morning of 21 March eighteen Mosquito FB.VIs of No. 140 Wing RAF – from No. 21 Squadron RAF, the Australian No. 464 Squadron RAAF and the New Zealand No. 487 Squadron RNZAF – took off from Fersfield airfield in Norfolk, together with two Mosquitos carrying photographic equipment. The raid was formally led by the commander of No. 140 Wing, Group Captain Bob Bateson, but the commander of No. 2 Group, Air Vice-Marshal Basil Embry, also flew on it under the assumed name “Smith”. Cover was provided by some 30 RAF P-51 Mustang fighters, which were also to attack anti-aircraft positions. The aircraft crossed the North Sea at a height of a few dozen feet to evade German radar; salt spray settled on the cockpit windscreens. Over Zealand the formation split into three waves of six aircraft, which were to strike the target in turn, a few minutes apart. The bombs had delayed-action fuses so that the explosions would not catch the following aircraft. The time of the attack – around 11.15 a.m. – was chosen with the lunch break in mind, when the building was expected to be relatively empty and the filing cabinets open.

The first wave found the target without difficulty – the Shellhus was the only building in the city painted in camouflage colours. The bombs struck the lower storeys: the Mosquitos were meant to hit the walls of the building from the side, not from above. Over a goods yard, however, the Mosquito of the commander of No. 21 Squadron, Peter Kleboe, clipped a tall floodlight mast. The damaged aircraft shed its bombs over Sønder Boulevard – eleven or twelve people were killed in the tenement that was hit – and crashed onto garages on Frederiksberg Allé, right beside the Catholic school Institut Jeanne d’Arc, known as the French School (Den Franske Skole) and run by nuns. Both airmen were killed.

The garages caught fire. The second wave came in from a slightly different direction, and several pilots, seeing clouds of smoke over Frederiksberg, took them to be the burning Shellhus. Bombs fell on the school and the neighbouring blocks on Maglekildevej and Amicisvej. Only some of the aircraft in the second wave found the right target; one bomb blew out the stairwell windows of the Shellhus and killed many Gestapo staff fleeing the building after the first strike. In the third wave only its leader recognised the mistake; he flew over the Shellhus but did not drop his bombs, while the others attacked the area around the school, dropping incendiaries as well.

The Shellhus

The west wing of the six-storey building was almost razed to the ground and the whole structure burned from end to end. Most of the Gestapo’s files were destroyed. Twenty-six Danish prisoners were held on the top floor. The RAF had reckoned that they would all die in the rubble; in the confusion, however, eighteen of them managed to escape. Danish witnesses later believed that the pilots had deliberately bombed the lower floors to spare the prisoners – in reality this was simply the technique of a low-level attack. Among those saved was the physician Mogens Fog, a member of the Danish Freedom Council. Eight prisoners were killed, among them Rear Admiral Carl Hammerich and officers connected with army intelligence. According to English-language accounts, 55 Germans and 47 Danish employees of the Gestapo were also killed in the building; other figures speak of some 125 dead in and around the Shellhus altogether, many of whom were never identified – remains were still being recovered from the ruins in the summer of 1945.

The raid paralysed the Gestapo’s work in Copenhagen for crucial weeks before the end of the war. The destruction of the card indexes protected many members of the resistance from arrest, and the leaders who had been freed were able to return to their work. In military terms the mission had been accomplished.

The school

At Frederiksberg a tragedy unfolded. The attack came during lessons. Several hundred children were in the school – some were killed by the explosions, some in the cellars where they had taken shelter during the alarm and which were buried by rubble, and some in the fire. Local residents, firemen and survivors themselves tried to dig the children out of the rubble before the fire engulfed the whole building; two fathers, two firemen and volunteers were killed in the attempt. The rescue was hampered by the HIPO, who cordoned off the area and would not let in parents searching for their children.

According to the most recent Danish tally, 86 children and 20 adults were killed at the school, among them ten nuns, teachers and rescuers; English-language accounts usually give 87 children and 18 adults. Some 900 residents of the surrounding houses were left homeless. The total number of civilian victims of the raid is estimated at 120–125; hospitals recorded 117 dead and more than 300 wounded, but in the chaos not everyone was registered. The school was never rebuilt – the surviving pupils were moved to the Institut Sankt Joseph.

The RAF also suffered losses. Anti-aircraft fire damaged several aircraft. One Mosquito ditched in the Øresund, drowning its crew, two others came down in the Kattegat, and a Mustang crashed in Fælledparken. In all, four Mosquitos and two Mustangs were lost; nine airmen were killed – Britons, Australians, New Zealanders, a Canadian and a Norwegian. The surviving crews were told what had happened to the school only after the end of the war in Europe.

The price of precision

Operation Carthage is regarded as one of the most daring precision raids of the war and, at the same time, as a warning against the illusions they fostered. It showed that even the most carefully planned low-level attack depended on chance – a single mast, a single plume of smoke. The mistake came less than three weeks after another Allied air force error in The Hague had destroyed the Bezuidenhout district, and in both cases the victims were the people of occupied countries whom the raids were meant to help. The difference was that in Copenhagen it was the Danes themselves – the leaders of the underground – who had asked for the attack and knew its risks. The prevailing view in resistance circles was that, despite the tragedy, the destruction of the archives had saved many people from arrest, torture and death.

For the families of Frederiksberg, however, the mourning lasted for decades; for a long time it was spoken of more quietly than the heroism of the resistance. On 23 March 1953 a memorial was unveiled on the site of the school, and the names of the victims were carved into paving slabs on Frederiksberg Allé. In 1951 a plaque commemorating the eight prisoners who had been killed was placed on the new Shellhus building. In 2021 the Danish director Ole Bornedal recalled the tragedy in the film The Shadow in My Eye (Skyggen i mit øje).

The last weeks of the occupation

The Copenhagen raid was one of the last major RAF strikes in Denmark. A similar attack on the Gestapo headquarters in Odense was planned for 17 April 1945. By then the Germans were holding hundreds of thousands of soldiers and refugees from East Prussia and Pomerania in Denmark, and the underground was preparing to take over power at the moment of surrender. The occupation of Denmark ended in the first days of May 1945, when the German forces in north-western Germany, the Netherlands and Denmark surrendered to Field Marshal Montgomery. The Danes came out of the war as a country that had managed to save most of its citizens – Jews included – but the memory of 21 March 1945 remained one of the most painful of the occupation.