The resistance in Jutland was collapsing from the inside. In December 1943 the Gestapo caught a British-trained paratrooper, Jakob Jensen, in Aarhus; under interrogation he gave up the supply networks across the peninsula, and 145 people were arrested as a result — among them the Hvidsten Group, taken on 11 March 1944. Then, in the spring, the Gestapo recruited Grethe Bartram from communist and resistance circles in the city as an informant. She named some fifty people. Group after group came apart, including the Samsing Group in June. Weapons stopped arriving, and the men who knew where the remaining weapons were kept were sitting in dormitories 4 and 5, in offices the Germans had installed in rooms built for students, next to the archives that recorded everything they had said.

The force lifted off from Swanton Morley in Norfolk on the morning of 31 October, the first aircraft rolling at 8:40 and all thirty-three airborne by 9:20. It comprised twenty-four Mosquito Mk.VI fighter-bombers from three squadrons of 140 Wing, one Mosquito Mk.IV of the RAF Film Production Unit to record what happened, and an escort from 315 (Polish) Squadron — twelve Mustang Mk.IIIs on paper, eight in practice, after four were found that morning with broken tail wheels. The Mosquito was made largely of wood and was fast enough at low level to arrive before the sirens did. The timing was deliberate in another way too: mid-morning meant Gestapo staff would be at their desks, while most Danish prisoners were expected to be elsewhere at lunch.

The first bombs went off at 11:41. The attack came in waves, one after another: the leading aircraft carried high explosive to break the buildings open, the last two waves incendiaries to set the paper alight. The bombs were fused with an eleven-second delay so the aircraft that dropped them would be gone before they detonated. Dormitories 4 and 5 were hit. The Langelandsgade barracks, a secondary target, were badly damaged. One bomb went into the university's main building, which was still under construction, and there it killed men who had nothing to do with the war on either side. Most of the Gestapo archive burned, including much of the file on the Danish resistance. Nobody has ever established exactly how much was lost.

A German internal report counted 39 dead in the dormitory offices: 27 SS officers working for the Gestapo, among them the Aarhus commander Eugen Schwitzgebel, and 12 from other German police departments, most of them clerical staff. Another twenty were killed at the Langelandsgade barracks, eighteen of them soldiers. About ten Danish civilians died as well. Several were builders working on the unfinished main building; the chief architect, C.F. Møller, was injured. One Danish prisoner was killed while under interrogation. Ruth Philipsen, whose arrest had prompted the telegram, came through it almost unhurt. So did the resistance leader Harald Sandbæk, who was being interrogated at the moment the bombs arrived — badly injured, treated in secret, and eventually got out to Sweden. One Mosquito was hit by flak from the German light cruiser Nürnberg and was too damaged to cross the North Sea; escorted over the Kattegat, it landed safely in Sweden, where the crew destroyed the aircraft before Swedish authorities reached them. They spent the rest of the war interned.

The RAF afterwards called it the most successful operation of its kind in the war, and by the standard applied to it — records destroyed, headquarters wrecked, precision achieved from rooftop height in daylight over a friendly city — the claim is hard to argue with. The Germans responded by reinforcing, nearly doubling the number of Gestapo agents in Denmark. Aarhus was left with a more complicated inheritance. The raid was requested by Danes, aimed at a Danish university, and it killed Danes: workmen on a building site, a prisoner in a cell. Bennike knew that would happen when he sent the telegram, which is the part of the story that does not resolve. The university buildings were repaired and remain in use.