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The Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United States during the Second World War in order to obtain the industrial resources to exploit the military potential of the research and development (R&D) work completed by the UK up to the beginning of World War II, but that Britain itself could not exploit due to the immediate requirements of war-related production. It received its popular name from the program's instigator, Henry Tizard. Tizard was a British scientist and chairman of the Aeronautical Research Committee, which had propelled the development of radar.

The mission travelled to the United States in late September 1940 during the Battle of Britain. They intended to convey a number of technical innovations to the U.S. in order to secure assistance in maintaining the war effort.


The objective of the mission was to cooperate in science and technology with the U.S., which was neutral and, in many quarters, unwilling to become involved in the war. The U.S. had greater resources for development and production which Britain desperately wanted to use. The information provided by the British delegation was subject to carefully vetted security procedures, and contained some of the greatest scientific advances made during the war: Radar (in particular the greatly improved cavity magnetron and design for the VT fuse), details of Frank Whittle's jet engine and the Frisch-Peierls memorandum, which described the feasibility of an atomic bomb. Though these may be considered the most significant, many other items were also transported, including designs for rockets, superchargers, gyroscopic gunsights, submarine detection devices, self-sealing fuel tanks and plastic explosives.

Although Britain was interested in the Norden bombsight, when President Roosevelt apologised and said that it was not available to Britain unless it could be shown that the Germans had something similar (Tizard was not unduly dismayed as he thought there were other US technologies more useful to Britain than the bombsight), Tizard asked if he could have the external dimensions of the unit, so that British bombers could be modified to take it, if it became available at some future date.[1] The American Congress had many proponents of neutrality for the USA and so there were further barriers to co-operation. Tizard decided that the most productive approach would be simply to give the information and use America's productive capacity. Neither Winston Churchill nor the radar pioneer, Robert Watson-Watt, were initially in agreement with these tactics for the mission. Nevertheless, Tizard first arranged for Archibald Hill, another scientific member of the committee, to go to Washington to explore the possibilities. Hill's report to Tizard was optimistic.

Moving the secrets

After Churchill's approval for the project, the team began gathering all technical secrets which might have military use. At the end of August, Tizard went to the U.S. by air to make preliminary arrangements. The rest of the mission would follow by ship. They were:

All the documents were gathered in a small trunk: a lockable metal deed box, used for holding important valuable documents such as property deeds. Bowen was allowed to take 'Magnetron Number 12' with him. After spending the night under Bowen's hotel bed, the case was strapped to the roof of a taxi to the station. An over-eager railway porter whisked it from Bowen at Euston Station to take it to the train to Liverpool and Bowen almost lost sight of it. Inconsistently, in Liverpool the magnetron was given a full Army escort. According to James Phinney Baxter III, Official Historian of the Office of Scientific Research and Development: "When the members of the Tizard Mission brought one to America in 1940, they carried the most valuable cargo ever brought to our shores".[4] The British magnetron was a thousand times more powerful than the best American transmitter at the time and produced accurate pulses.[5] The team arrived in Halifax in Canada on 6 September and went on to Washington a few days later. The team of six assembled in Washington on 12 September 1940.


Tizard had met Vannevar Bush the chairman of National Defense Research Committee on 31 August 1940, and arranged a series of meetings with each division of the NDRC. When the American and British teams met, there was initially some cautious probing by each side to avoid giving away too much without getting anything back in exchange. At a meeting hosted by NDRC's two-month-old "Microwave Committee" chairman Dr Alfred Loomis[6] at the Wardman Park Hotel on 19 September 1940 the British disclosed the technical details of the Chain Home early warning radar stations. The British thought the Americans did not have anything like this, but found it was virtually identical to the US Navy's longwave CXAM radar. The Americans then described their microwave research done by Loomis and Karl Compton earlier in 1940. The British realised that Bell Telephone Laboratories and General Electric both could contribute a lot to receiver technology. The Americans had shown a Navy experimental shortwave 10-centimetre wavelength radar but had to admit that it had not enough transmitter power and they were at a dead-end. Bowen and Cockcroft then revealed the cavity magnetron, with an amazing power output of about ten kilowatts at 10 centimetres.[6] This disclosure dispelled any tension left between the delegations and things then went smoothly. The magnetron would enable the production radar units small enough to be installed in night-fighters, allow aircraft to locate U-boats and would provide great navigational assistance to bombers. It is considered to be a significant factor in the Allied victory in the Second World War.[5]

Bowen stayed in America and a few days later, at the General Electric labs in New Jersey, he showed the Americans that the magnetron worked. The Bell Telephone Company was given the job of making magnetrons, producing the first thirty in October 1940, and over a million by the end of the war. The Tizard mission caused the foundation of the MIT Radiation Lab, which became one of the largest wartime projects, employing nearly 4,000 people at its peak.

The Tizard delegation also visited Enrico Fermi at Columbia University and told Fermi of the Frisch-Peierls concept for an atomic bomb. Fermi was highly sceptical, mainly because his research was geared towards using nuclear power to produce steam, not atomic bombs. In Ottawa, the delegation also met a Canadian, George Laurence, who had secretly built his own slow neutron experiment. Laurence had anticipated Fermi's work by several months.

When they returned to the UK in November 1940, the delegation reported that the slow neutron researches being conducted by French exiles in Cambridge, Columbia (by Fermi) and Canada (by Laurence), were probably irrelevant to the war effort. But since nuclear boilers could have some post-war value, they arranged for some financial support for the Canadian fission experiments. George Laurence later became involved in the secret exchanges of nuclear information between the British and the Americans. The British did not realise the atomic bomb was a serious possibility until Franz Simon reported in December 1940 to the MAUD Committee that it was feasible to separate the isotope uranium-235.

Tizard met with both Vannevar Bush and George W. Lewis and told them about jet propulsion, but he revealed very little except the seriousness of British efforts. Bush later recalled: "The interesting parts of the subject, namely the explicit way in which the investigation was being carried out, were apparently not known to Tizard, and at least he did not give me any indication that he knew such details".[7][8]

Later Bush realised that the development of the Whittle engine was far ahead of the NACA project. In July 1941 he wrote to General "Hap" Arnold, commander of the USAAF, "It becomes evident that the Whittle engine is a satisfactory development and that it is approaching production, although we yet do not know just how satisfactory it is. Certainly if it is now in such state that the British plans call for large production in five months, it is extraordinarily advanced and no time should be lost on the matter".[8] Bush recommended that arrangements should be made to produce the British engine in the United States by finding a suitable company.[8]


Although the Tizard mission was hailed as a success, especially in radar, it is possibly significant that on his return to London on the 8 October 1940, Tizard found that his job no longer existed.

Although the German bombing of the UK was largely over by the time that the new radar systems were in production, the technology such as aircraft radar and LORAN navigation greatly helped the Allied war effort in Europe and the Pacific, for example almost eliminating the threat from German submarines.

The main success of the mission had been the transfer of radar technology, but the mission also opened up channels of communication for jet engine and atomic-bomb development and is seen as one of the key events in forging the Anglo-American alliance. However, the UK was in a desperate situation and was compelled to release technology that had immense commercial value after the war.


  1. Zimmerman 1996, p. 99.
  2. John Cockcroft would receive a Nobel prize in 1951
  3. Brown, Minnett & White 1992.
  4. Baxter III 1946, p. 142.
  5. 5.0 5.1 Hind 2007.
  6. 6.0 6.1 Conant 2002, pp. 168–169,182.
  7. Zimmerman 1996, p. 120.
  8. 8.0 8.1 8.2 Dawson 1988, Chapter 3.



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