Death by Blue Peacock Britain’s Bizarre and Deadly Cold War “Rainbow Codes”

In the world of modern weaponry, a good name can go a long way when it comes to the intimidation factor. Names like “Hellfire”, “Sidewinder”, “Stinger”, and “Javelin” convey menace and devastating firepower, making it abundantly clear that you wouldn’t want to be on the receiving end of these weapons. But what if you were confronted by a weapon named “Blue Peacock, or “Green Bamboo,” or “Orange Poodle”? While such oddly-named weapons with such names might seem more likely to make the enemy die of laughter, these are in fact real codenames used by the British Military during the early days of the Cold War. And though they may seem outwardly laughable, these names served a deadly serious purpose. This is the strange tale of the Rainbow Codes.

In military security, codenames serve to obscure the purpose of an operation, person, or piece of equipment while providing an easy-to-remember designation for everyday use. Therefore, for maximum security, a codename should be completely random and have nothing to do with what it is protecting. However, one group that doesn’t seem to have gotten the memo are the Nazis. Throughout the Second World War, German military administrators, seemingly unable to help themselves, indulged in the unfortunate habit of bestowing secret weapons and operations with meaningful, symbolic names, often drawn from Germanic mythology. Consequently, Allied intelligence agencies were often able to work out the meaning of codenames from context alone.

For example, early in the War, the German Luftwaffe and British Royal Air Force were engaged in a shadowy arms race known as the “Battle of the Beams.”  In September 1940, as part of the larger campaign now commonly known as the “Blitz”, the Luftwaffe began round-the-clock strategic bombardment of London and other major English cities in the hopes of forcing Britain to sue for peace. While bombing at night made the German bombers less vulnerable to British fighter aircraft and antiaircraft guns, it also made it much harder for them to find their targets. Consequently, the Germans developed an electronic navigation aid known as Knickebein [“kuh-nick-uh-bye-n”] or “crooked leg”. The system used a pair of transmitters based in mainland Europe to project a pair of overlapping radio beams over the intended target. If the bomber pilot flew straight along the beam, he heard a continuous tone; if he strayed to the left or to the right, he head a string of Morse code letters. Knickebein was used successfully for several months until the British learned of its existence and developed countermeasures to jam the system – whereupon the Germans switched to a more sophisticated system known as X-Gerät, [“Gerr-ate”], which used multiple beams that intersected over the target. This, too, proved highly effective at first, and was largely responsible for the success of the November 14, 1940 raid that devastated the city of Coventry. Eventually, however, the British worked out how X-Gerät worked and once again succeeded in jamming the signal.

Wary that the Germans would try again, R.V. Jones, Britain’s Assistant Director of Scientific Intelligence, set out to identify the next electronic navigation system and develop countermeasures before the Germans could even field the new device. Combing through German Enigma messages – which British codebreakers had recently cracked – Jones discovered references to a mysterious device codenamed “Wotan.” Consulting with an expert on German culture, Jones discovered that “Wotan” or “Odin” was the one-eyed king of the Gods in Norse and Germanic mythology. Knowing of the German’s love of meaningful codenames, Jones deduced that “Wotan” was likely a single-beam navigation system. He turned out to be correct: Wotan, also known as Y-Gerät, worked by transmitting a signal from a ground station to a receiver aboard the bomber aircraft, which then transmitted its own signal back. In this manner, the position of the aircraft could be accurately determined. Armed with this educated guess, Jones sent out aircraft equipped with radio receivers to track down the beams. Unfortunately for the Germans, their choice of  45 MegaHertz for Y-Gerät turned out to be a poor one, for it just so happened to match the transmitting frequency of the dormant pre-war BBC television transmitter at Alexandra Palace. Using this transmitter, Jones was able to send false, distorted signals back to the German bombers, causing them to drift off-course and drop their bombs over empty countryside. When the Germans eventually discovered the jamming, they abandoned the radio navigation concept entirely – a defeat brought about in part by a poorly-chosen codename.

Later, in August 1944, German navy Sub-Lieutenant Hans-Joachim Förster, commanding the Type VII U-boat U-408, achieved a remarkable feat by sinking two warships and two merchant ships in the English Channel in the span of five days. Though Allied submarine hunters scoured the area mercilessly, strangely none were able to detect U-408, and none of the 92 depth charges they dropped came anywhere close to the submarine. Shortly thereafter, other ships began reporting encounters with similarly undetectable “phantom U-boats”, baffling Allied military analysts. Soon, however, interrogations of captured U-boat crewmen revealed that the Germans had begun experimentally covering U-boats with a strange coating composed of thick rubber tiles covered in small dimples. At first, the purpose of this coating eluded Allied scientists, who theorized that it offered protection against depth charges or greater underwater speed – similar in principle to the dimples on a golf ball. However, experiments quickly discredited both theories. It wasn’t until prisoner interrogations and decrypted Enigma intercepts revealed the name of the coating – Alberich [“Ahl-burr-rick”] – that the Allies realized its true purpose. In Norse and Germanic folklore, Alberich is the magical king of the Dwarves who possesses the ability to become invisible. The Allies thus deduced that the coating was intended to absorb sound waves and make U-boats invisible to ASDIC, an early form of sonar. However, only a handful of U-boats were ever fitted with Alberich – too few and too late to have any significant impact on the course of the war.

This is not to say that the Allies weren’t above employing meaningful codenames for their own amusement. For example, in 1943, British Intelligence launched Operation Mincemeat, an elaborate deception meant to divert German troops away from Operation Husky – the planned Allied invasion of Sicily. The operation involved dressing up a dead body as a fictitious military officer, packing its briefcase and pockets with fake documents, and dumping it off the coast of  neutral Spain. It was hoped that the documents – which indicated that the Allies would land in Greece, not Sicily – would eventually find their way into German hands. Though the mastermind of the operation, Lieutenant Commander Ewen Montagu, was offered a selection of randomly-generated codenames, he chose “Mincemeat” largely so he could announce the success of the operation with the thematically appropriate message “Mincemeat Swallowed Whole” – and for more on this strangest of deceptions, please check out our previous video The Bizarre World War II Plan to Score a Major Victory for the Allies.

Having learned a valuable lesson from the Germans, at the end of the war the British Ministry of Supply developed a foolproof scheme for generating truly random codenames, known as the Rainbow Codes. The system worked by pairing a random colour with a random noun, creating easy-to-remember codenames that were by design completely unrelated to the project they were meant to conceal. While effective, the system resulted in some truly bizarre and decidedly un-intimidating combinations, such as “Green Cheese” – a nuclear-tipped anti-ship missile; “Orange Poodle” – an early-warning radar; and “Yellow Duckling” – an infrared-based submarine detector. Others were slightly more intimidating, such as “Black Knight” – a rocket test vehicle; “Blue Steel” – a nuclear air-launched standoff missile; and “Red Rapier” – an air-launched cruise missile. Occasionally, these random combinations actually resulted in meaningful names, such as “Black Maria” – slang for a police van; “Red Duster” – a nickname for the Red Ensign, the flag flown by British merchant ships; “Blue Danube,” “Blue Moon”, “Blue Streak”, and “Yellow Sun.” And in case you are wondering, these codenames refer to, respectively: an aircraft Identification Friend or Foe or IFF device; an antiaircraft missile; a nuclear warhead; two intercontinental ballistic missiles; and a nuclear weapon casing, meant to house the “Green Grass” and “Red Snow” warheads.

But the weapon with perhaps the most deceptive Rainbow Code name was “Blue Peacock”, also known as “Blue Bunny” or “Brown Bunny.” Despite the cuddly image conjured by those names, Blue Peacock was truly horrific in concept. Essentially a nuclear land mine, the weapon consisted of a ten-kiloton “Blue Danube” warhead meant to be buried along the European border with the Soviet Union. In the event of a Soviet invasion of Western Europe, the mines would be detonated by remote control, obliterating large numbers of Soviet troops and heavily irradiating the border, rendering it impassable to further waves of invaders. To protect the warhead against the elements, it was housed in a 7-ton steel casing, internally pressurized to prevent water from leaking inside and fitted with anti-tampering switches that would detonate the weapon if it was moved. However, the design suffered from one major flaw: in the winter, the weapon could potentially get so cold that its detonating mechanism would be rendered inoperative. Several conventional solutions were suggested, such as wrapping the weapon in insulating blankets, but one proposal was so out of the box that it has gone down in history as one of the most bizarre and outlandish plans in the history of warfare. The plan called for – and we can’t make this stuff up – live chickens to be placed inside the weapon’s protective case and provided with a supply of food, water, and air. This would keep the chickens alive for about a week, during which time their body heat would keep the detonating mechanism at a functional temperature. Thankfully for PETA members everywhere, this bonkers plan was never implemented; indeed, the whole Blue Peacock project soon eventually abandoned as it was realized that intentionally nuking an allied nation’s territory was perhaps taking things a bit too far. Being top-secret, all records of Blue Peacock were sealed in the archives and the whole scheme forgotten until April 1, 2004, when the documents were finally declassified. Given the date, the media naturally assumed that the whole “Chicken Powered Bomb” proposal was some sort of elaborate practical joke, forcing Tom O’Leary, head of education and interpretation at the National Archives, to appear before the press and solemnly assure them that:

“It does seem like an April fool but it most certainly is not. The Civil Service does not do jokes.”

The Rainbow Codes system was used until 1958, when the Ministry of Supply was broken up and its duties divided between the War Office, the Air Ministry, and the civilian Ministry of Aviation. In its place, the various services adopted an alphanumeric code system consisting of two random letters paired with three random digits – such as the WE.177 series of air-dropped tactical nuclear bombs. But while such codes arguably do an even better job of concealing their true purpose, one has to admit they lack the quaint charm of the Rainbow Codes, a relic of a more innocent time when one could officially name a world-ending nuclear weapon “Brown Bunny” and still keep a straight face.

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Expand for References

Johnson, Brian, The Secret War, The Anchor Press, Ltd, Tiptree, England, 1978


“Stealth” U-Boats, Deutsches U-Boot Museum,


U-Boat U-480: the Hunt for Nazi Germany’s Rubber Stealth Submarine, YouTube,


The Real Meaning of the Words: a Pedantic Glossary of British Nuclear Weapons,


Gibson, Christopher, United Kingdom Aerospace and Weapons Projects,


Cold War Bomb Warmed by Chickens, BBC News, April 1, 2004,


Edwards, Rob, British Army Planned Nuclear Landmines, New Scientist, July 16, 2003,


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