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The small box that won the war

As last week was an anniversary of the end of WWII, I wanted to share something that I found really fascinating when I learnt about it. Caveat: I did not fact-check this article and wrote it mostly from memory, so some things may be incorrect. But in any case, the story is true. The title may be a bit exaggerated, but only just. There really was a box that contributed more to ending WWII than most armies.

The impact of military on technological progress is huge and undeniable. It’s enough to look at where the first main tech clusters were. Most, if not all, of them had 3 components: university (ideas), military (early users) and entrepreneurs (linking the two). For example, this is the case for Silicon Valley, Cambridge (UK), Israel.

World War II gave a big boost to development of radio and, more specifically, radar technology. The acronym RADAR came from the military and stands for Radio Detection And Ranging, hinting at its main use case. Both Britain and Germany developed massive terrestrial radar networks for air raid detection. Britain for one had massively improved the radar technology and coverage before the war and was frantically working on further improvements. That deserves another post since it is also super interesting. Germany had all of Western Europe covered in radar stations.

When the war broke out, Britan became somewhat busy and financially strained with all the air raids and putting out fires in London. But it also had some very clever tech sitting around. So, in 1940, the decision was made to give most important technologies to the US in exchange for their financial and industrial help. The official version is that Britain realised that it couldn’t produce things in volume while the US could. An alternative explanation is that the country didn’t want these technologies to go to the Nazis if (or when as it may have seemed then) the country falls. The third possible reason was that Britain was getting broke as the gold with which it was paying for materials from the US was running out. I assume it was already negotiating (or at least lobbying for) a loan from the US – Churchill sent a letter on the subject to Roosevelt in December 1940. That eventually led to the beginning of the lend-lease programme in early 1941. So it’s easy to see a likely financial connection in the “goddwill gesture” of sharing the tech secrets. I don’t know which explanation is more true. Possibly all are.

In any case, in August 1940, a young scientist called Edward George Bowen woke up in a hotel in London with something that is now called the "Tizard's briefcase" under his bed. It was a lockable metal box, used for holding important documents such as property deeds. The two of them took a taxi to Euston Station (Bowen inside, the box tied to a roof for some reason), where they intended to board a train to Liverpool.

At Euston Station a porter grabbed the box and rushed ahead to the train not waiting for his client. Bowen almost lost sight of him – and hence of the box. He later said, “The only way to keep track of him, was to watch the box weaving its way through the mass of heads upfront.” That probably doesn’t look like a major event – except when you know the contents of the box. This is how a BBC article describes it:

“Inside lay nothing less than all Britain's military secrets. There were blueprints and circuit diagrams for rockets, explosives, superchargers, gyroscopic gunsights, submarine detection devices, self-sealing fuel tanks, and even the germs of ideas that would lead to the jet engine and the atomic bomb.”

Bowen boarded a ship bound for Canada. The instructions were to throw the box overboard if the ship was attacked. Small holes had been drilled in its sides to keep it from floating. That didn’t happen and the box eventually made it to the US, together with a group of scientists representing different disciplines, and was presented to the US military and scientists.

This is now referred to as Tizard Mission, after Henry Tizard, who came up with the idea and headed the mission.

Why do I say that this box won the war? Well, 2 things mainly:

Cavity magnetron, one of the items in the box was a device, which eventually led to mass produced airborne radar. First radars operated on wavelengths that made them big - big device, big antenna. Hence, they were based on land (and did a lot to detect air attacks for both Britain and Germany). There were some radars on airplanes, but those were either experimental or slowed airplanes down a lot (I saw somewhere that in one case the reduction in speed was 50(!) mph) – basically were not practically useful, especially in combat. But with cavity magnetron a secret lab created in MIT developed portable airborne radar by early 1941. Following that they were mass produced and went into American and British planes. I believe some even made it to the Soviet Union.

The importance of this is hard to overestimate. Previously the planes had no reliable way of detecting enemy aircraft. The prevailing method of hearing bullets pierce you plane was clearly not optimal. Using your eyes was another approach, but of course, that also had issues, like dealing with bad weather conditions, darkness, humans not seeing far enough or missing things, and more. On-board radar changed all that.

Germany had theirs as well, but using a different technology, which was clunkier and less accurate. In any case, cavity magnetron at least levelled the playing field, but probably created an advantage for the Allies.

If that wasn’t enough, there was a second thing.

The Tube Alloys programme was the first nuclear weapons project taking place in Britain and Canada. The results were also in the “Tizzard Box”. This triggered the signing by the United Kingdom and the United States of the Quebec Agreement, under which they agreed to share nuclear weapons technology, and to refrain from using it against each other, or against other countries without mutual consent. The technology became part of the Manhattan Project, which, as the whole world knows, developed the first nuclear bomb. That bomb was eventually used to force Japan to capitulate.

Not bad for two contributions of a small box, almost lost at Euston Station and not thrown overboard in the ocean.


In 1942 the United States made a decision to develop the atomic bomb project independently, despite an agreement of unrestricted scientific interchange between the US and Britain. Following that, it did not provide complete details of the results of the Manhattan Project to the United Kingdom. I would venture that until the end of the war that issue was lower on British agenda than defending itself and keeping the lights on. And after the war, the focus switched to rebuilding and climbing out of the financial hole. The US unilaterally and abruptly ended Lend-Lease in 1945. The war seriously damaged UK economy and infrastructure, so the country had to ask (more like beg as I understand it) for more loans from the US and Canada. (Which by the way were only repaid in 2006). Considering the history of WWI loans (still not returned in full), this couldn’t have been an easy process.

In the meantime, the Soviet Union possibly had more information about it than the Brits since it had a network of spies infiltrating both the British and American projects, including a member of the famous Cambridge Five and the woman Einstein was living with.

That´s how Britain went from being in the front to having to catch up in the area of nuclear technology – one of the ways the war hit the country. Not the worst of all, I’d say, but a curious development.

Another technology born from the Tizzard Box is the turbojet engine that went into the jet planes later built in the UK and the USA. Initial beneficiaries - General Electric and Pratt & Whitney in the US and Rolls-Royce in the UK. Rolls-Royce sold a version of its engines to the Soviet Union, which at least contributed (since the Russians had their own programme as well) to the engines that powered Russian jets, including famous MIGs.

Interestingly, you are probably using cavity magnetron in your daily life, similar to many technologies that first appeared in military applications. This one led to the creation of the microwave oven. So, your kitchen has something that helped to win the Battle for Britain.