5 Detective Tricks That Dug Up Wartime Secrets

5 The Water Ruse

During World War II, the opposing sides listened to each other’s messages, struggling to decode them. This is different from listening to each other’s messages and struggling to decipher them. With a cipher, there’s a process for translating the characters in a message, and once you know it, you can encipher and decipher whatever you want. With a code, each word or idea is replaced by something specific and unique (e.g., Bob becomes “buttking”), and even if you’ve decoded previous messages, you will be totally stumped by some new word you’ve not seen before.

In 1942, the American military was looking at one Japanese codeword: “AF.” It represented some potential naval target. The Americans had an inkling that this could be the Midway Atoll, based on how the war was going, but they didn’t know for sure. So, they told contacts on Midway to broadcast a radio message, saying that their desalination plant was down. Command sent this request to Midway over a secure telecommunications cable but told Midway to broadcast the radio message on the open airwaves.

Pretty soon, new Japanese messages that we intercepted were talking about how the fresh water situation in AF was a mess. That confirmed it: AF was Midway. By listening to later messages, the Americans knew not just that Midway would be hit but the exact date and the exact approach the Japanese were taking. Even though Japan thought they were the ones setting up an ambush, Japan suffered 10 times the amount of losses America did in the resulting battle. It was perhaps the greatest naval defeat of all time — or, to put that in military speak, crazy AF. 

4 The One-Eyed God

Here’s another codeword the Allies had to puzzle over: Wotan. “It is proposed to set up Knickebein and Wotan installations near Cherbourg and Best,” read one Enigma message (Britain deciphered the message, but the challenge of decoding remained). We knew what Knickebein meant. It referred to a new type of antenna, and it also happened to be the name of a bird from Norse mythology, one who could see far. But what was Wotan?

If the Germans were going for a mythology theme, maybe Wotan meant Wōden. This was a god, one associated with ravens, the one for whom Wednesday is named and a fellow you might know better as Odin.

Knickebein could see far. What about Odin? He had a noted sense of sight as well, notable mainly in that it consisted of one single eye. So, codebreakers scratched their chins and figured, what if Wotan refers to something else that is able to see in such a singular manner? Say, a type of antenna that uses a single beam? The Germans could be shooting a beam toward planes, and a radar station could measure how long the beam takes to return, and that’s how they’d be able to pinpoint where the plane is.

This logic turned out to be totally correct. Let that be a lesson to you: When setting codewords, don’t aim for cleverness. Unless you’re a serial killer with an urge to leave clues, just pick a random word. “Buttking” works well. 

3 The Price of Oranges

When planes bombed targets during the war, headquarters didn’t always have a good way of knowing how successful the raid had been. The pilot himself had orders to get out of there as quick as possible, and in the dark of night, there was no telling what physical structures lay in the site of that explosion. 

If planes targeted railroad bridges in France, for example, they didn’t always stick around to see if the bridge really went down. Luckily, there was a simple way to detect disruptions in trade. If the bridge fell, the price of oranges in Paris went up.

The Germans targeting London, meanwhile, had their own potential source of intel on bombers’ success…

3 The Ben Boom

Every night at 9 p.m., the BBC broadcast Big Ben chiming, live. By listening to any background sounds unintentionally captured around that bell, it may have been possible for Germans listening to the radio to calculate how close their bombs had fallen to their targets.

The way this story sometimes gets told, the Germans were even able to use noise around the chime to figure out weather conditions in London, and to plan future raids accordingly. That part appears to be just an urban legend, but the British did acknowledge the possibility that the Germans could get info out of the broadcasts. So, the BBC temporarily switched to a recording of the bell, while still claiming it was live. 

Funny thing, though: It wasn’t a very good recording, and thanks to one flaw that played every time, observant British listeners soon realized they were being lied to. For a while, some of these listeners at home feared that the reason the BBC switched to a recording was that German bombers had scored a bull’s-eye and the real tower and bell were now gone.

1 The Postcard Review

The BBC got into the intel game in 1942 as well. That was the year they had Director of British Naval Intelligence Admiral John Godfrey on, asking everyone to send in postcards and vacation photos they had of the European coast. People complied, and the War Office found themselves with an unprecedented collection of coastal imagery. When the time was right, they used these delightful photos to decide Normandy was the best spot to hit on D-Day. 

People submitted some 10 million photos and postcards in response to that request. The number of listeners who responded was around 800,000, which means people sent in an average of more than 100 pics each, which is its own kind of crazy. Maybe the most surprising part is that when the war finished, the government posted the vast majority of the submissions back to their original owners, which they were hardly obligated to do.

Today, of course, we’d never have need for this exact sort of crowdsourcing campaign, thanks to satellite imagery. Rest assured, however, that the government is using photos from social media and VR cameras to map the interior of every single residence, in case they should ever find a need for such info. 

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