Oslo Report, the mysterious document on Nazi weapons investigations submitted to the British anonymously in 1939

Barely a month after the start of the WWII the British embassy in Oslo received a mysterious unsigned letter offering to information detailed information about the latest generation weapons that Germany was developing.

That sowed confusion in the secret services because it did not come from any known agent and a priori it sounded like a cheat. However, his instructions were followed and a week later a complete document arrived that has gone down in history as the Oslo report.

was the captain Hector Boyes, a captain in the Royal Navy who served as a naval attaché at the legation, the addressee of the initial epistle. On November 4, 1939, he must have been stunned when he read the text, in which he was proposed, if he was interested, even a covert way of expressing his approval: changing the greeting made by the BBC broadcast for GermanyThe expression “Hullo, her ist London” (Hello, London speaking), repeating the greeting twice.

Drawing of thermoionic valves/Image: public domain on Wikimedia Commons

As at first sight there was nothing to lose, this was done and a week later a package containing the aforementioned report arrived at the embassy, seven pages typewritten, detailing the investigations of the Nazi regime in the field of weapons electronics and the companies collaborating in various programs, with express mentions of the wavelengths of the radars and the anti-aircraft countermeasures in which the Germans worked.

It also included Junkers bomber production statistics and the date of construction of what was to be the Kriegsmarine’s first aircraft carrier (although the report called it Franken, so it might be confused with the tanker of the same name). More important was the review of the design of small remote-controlled rockets and the description of the Rechlin airbase, where the Luftwaffe research laboratories were located.

Reginald Victor Jonesright, in 1987/Image: Laurent.seillier62380 on Wikimedia Commons

Another part of the report explained the two new types of torpedoes developed for submarines, some acoustic and other magnetic, as well as the operation of artillery projectiles by means of electric fuses, which replaced the classic mechanical means. In addition, it enclosed one of those pieces: a thermoionic valve or vacuum, capable of acting on electrical signals and that would be used as a sensor for the fuzes.

Sent to MI6 (British secret service for foreign affairs), surprisingly in London he was given no credibility and only a young physicist named Reginald Victor Joneswho would later be deputy director of the new scientific section of Intelligence, warned that the information was correct from a technical point of view, at least for the most part (there were some errors such as an exaggerated production of Junkers or the aforementioned confusion of the Frankenwhich was later found to be due to the fact that the author did not always have first-hand data).

Consequently, it could only be interpreted in two ways: either it was a propaganda stunt to show Teutonic technological superiority and sow discouragement in Britain or had they really hit on a informer contrary to Nazism and, therefore, of great value. The British command leaned towards the first option: tricks of the Abwehr, the German intelligence service; they had recently taken an SD hook (sicherheitsdienstSS counterintelligence) and it had cost them several agents, so they didn’t want to risk it again.

BEF soldiers embarking for France/Photo: public domain on Wikimedia Commons

After all, the British had just deployed in France their BEF (British Expeditionary Force) showing Hitler that they were ready to stop him and, indeed, their presence seemed to have been such a deterrent that the Wehrmacht did not dare to confront them and was satisfied with the invasion of poland. In a matter of a few months the error of that analysis would be clear on the beaches of Dunkirk.

The truth is without knowing who the author was from the report it was difficult to make a decision with certainty. Who could have such knowledge of the German investigation? Furthermore, why did he want to report it to the enemy? These questions were unanswered until in the spring of 1940 when the German army was on the march again, entering Denmark. It turns out that this was the country that, due to its neutrality, used the informer to send its messages.

It was called Hans Ferdinand Mayer. German, born in Pforzheim in 1895, he had studied Mathematics, Physics and Astronomy at the universities of Karlsruhe and Heidelberg, obtaining the doctorate for a work on electricity directed by a whole Nobel laureate, doctor Philip Lenard. In 1922 Mayer entered siemens to work on electronic circuits for communications and in 1936 became director of the company’s research laboratory in Berlin.

Thanks to that position I had access to extensive information about the work that was carried out in the country in terms of weapons applications of electronics, also having freedom to travel. And it so happened that Mayer not only he was not nazi If not the opposite; the invasion of Poland persuaded him to do what he could to put an end to that regime.

then moved to Oslo at the end of October and wrote the report in his room at the Bristol Hotel, making several copies using carbon paper. He also wrote a letter to Henry Cobden Turner, a British friend whom he had met working at the General Electric Company between the wars and who had helped him get a Jewish girl disowned by her Nazi father out of the country. He now asked him to keep in touch through another who was Danish, Niels Holmblad. That was how the documents arrived at the embassy. One of the copies is currently on display at the Imperial War Museum in London.

However, the invasion of denmark in April 1940 frustrated the possibility of continuing with the plan and on top of that Mayer was arrested by the Gestapo in 1943, accused of listening to the BBC and criticizing the government. They imprisoned him in Dachau but the intervention of his former teacher, the aforementioned Lenard, who was a devout Nazi, saved him from further punishment and he was transferred, passing through several concentration camps; His intellectual level helped make his captivity more bearable, destined for radio communications. Obviously, the Gestapo did not find out that he had done the Oslo report.

At the end of the war, he went to the US as part of the Operation Papercliporiginally called Overcast, which facilitated the transfer to that country of German scientists who had worked on weapons issues. There he researched at Wright-Patterson Air Force Base for the USAF. He later became a professor of Electrical Engineering at Cornell University and in 1950 returned to Germanyrejoining Siemens.

The Operation Scientists Paperclip/Photo: Public Domain on Wikimedia Commons

Reginald V. Jones revealed the existence of the Oslo report in 1947 but he still did not know his authorship and did not know it until 1953, although in a conversation with Mayer they agreed keep the secret to avoid possible reprisals from pro-Nazis.

In fact, not even his family knew about it until 1977, when he himself told them; he left it noted in his will on the condition that it be made public only on his and his wife’s death. Mayer died in Munich in 1980 and Jones waited with her until her death in 1989 to publicly unveil the enigma.


The Oslo Report 1939—Nazi Secret Weapons Forfeited (Frithjof AS Sterrenburg on V2ROCKET)/World War II covert operations (Jesus Hernandez Martinez)/The secret war. Spies, codes and guerrillas, 1939-1945 (Max Hastings)/Operation Crossbow. The Untold Story of the Search for Hitler’s Secret Weapons (Alan Williams)/Intelligence in War (John Keegan)/Wikipedia