#629-631 Limpet Mines and Fly Compasses

 Fun Fact #629

Flies, Wasps, and Boggerts 

When it comes to traversing battlefields one of the last things anyone ever wanted was to be caught with their fly down, but surprisingly it sometimes meant the difference between life and death.

In WW2 when allied pilots were shot down it was often up to them to find their way to a neutral country. The most famous was “The Comet Line” ending in Spain. However, finding their way required a good sense of direction leading to the invention of “The Fly Compass” where soldiers could balance specially made buttons to point north. This design started its life on flight jackets and shirts, however these articles of clothing were often ditched quickly to avoid detection leading forgetful pilots to ditch their compass. In response Allied manufactures moved the placement of these compasses to be the two fly buttons on flight pants so this vital tool couldn't be lost.

An issue arose, however, from the WASPs or “Women’s Airforce Service Pilots” since most women refused to wear men’s pants at the time, preferring to fasten their pants with buttons on the side in a style similar to skirts. This unintentionally led to many of these buttons becoming lost thanks to ripping off against the pilot seats in planes leading to a higher ratio of WASPs unable to find their way to rescue lines. While many women switched to Men’s trousers in response, the problem was never addressed and only saw improvement in the 1960s when women’s trends began favoring pants which fastened in the front.

Fun Fact #630

A Washout Failure

In WW2 communication behind enemy lines was vital to resistance groups and spy networks, and as such just about anything that could be used for communication was used for it. One of the most common examples were washing lines. 

Since washing lines were so common, they became a common means of sight-based communication by placing articles of clothing in specific orders. While a lack of records means that most “Clothes Codes” have been lost here are two of the most common: 

Morse code using closepins as “Dots” 

Useful when legitimate laundry had to be done at the same time making this the most common.

Common Code

Using a feature of the articles of clothing such as the first letter to spell out words or phrases, making it useful for secondary messages which were far harder for Axis powers to decipher.

EX: a handkerchief, eiderdown, lace and a pair of pants spelled the word “Help”

However here is where the problem begins, as pilots shot down and relying on Fly Compasses had to remove the buttons holding their fly closed just to use the compass. This in turn led to Pilots going out of their way to steal new pants and other articles of clothing, while clothes pins were stolen for use in bartering along their walk. This obviously led to issues of communication in areas along “Recovery Lanes”  for pilots. Worse yet it ruined the reputation of members who were victimized. One such example was “The Comet Line” to neutral Spain, where towns along the route invented legends of “Boggerts” who stole clothes of lazy people who left chores half-finished. 

Thus the Allies quickly got tired of complaints from victimized Spies and resistance groups. While recovered pilots complained about the lack of pockets in clothing in regions experiencing fabric rationing. The issue was never properly resolved and overtime resistance groups had to budget for replacement Clothespins. 

Image from Alamy.com

Fun Fact #631

The Saboteur Clampion

Snails are rarely seen as a threat, but in the hands of Allied Saboteurs, they quickly became the stuff of nightmares. In 1939 The British MIR Branch sought to develop new weapons, and seeing an article about “Super Magnets” in an article of Armchair Science they found an opportunity. Soon after they worked to create mines capable of being carried by divers and attached to ships, basing their design off of an aquatic Snail leading to the name: “Limpet Mines”. They quickly proved effective against supply ships and able to disable ships in strategic locations. Later a larger variant of Limpets was invented, dubbed “Clam Mines”. In fact Limpet mines are still a part of many militaries today –being cheap to make, hard to detect, and highly effective. 

Thanks to their success Limpet Mines were later adapted into smaller versions for use on-land called “Clam Grenades” and while they weren't as effective against land vehicles as hoped for, one point they were useful for was on Aircraft. By attaching a small spinner a Clam mine could be attached to enemy aircraft and only go off once a certain airspeed was achieved leading to planes appearing to have been shot down shortly after take-off. They were similarly hard to detect thanks to their small size and ability to be painted to match the colors of local aircraft.  In fact for awhile, some sections of North Africa and Italy suspected the Allies had a new way of detecting striking planes from a distance leading to their nickname of “Wraith Weapons” until the Clam Grenades were discovered to be the cause and the name “Wraith” was passed from a theoretical weapon to Clam wielding Sabetours. There have been no instances of these Grenades being used since the 70s, but thanks to their Analog design, they’d likely still be brutally effective against most planes today (provided the style of attachment changed), but thankfully Clams seem to have been forgotten and overlooked by terror organizations today.

While Clam grenades aren't made anymore, their legend in Italy as Wraiths later helped inspire fictional stories in various media including a personal favorite of mine: Wraith Squadron which is a book series set in the Star Wars Universe.

Testing of some of the earliest versions of Limpet Mines from a time when they were still made using condoms to waterproof the internal explosive, and hard candy which dissolved in water as the timing trigger for the explosive. At that time it cost around £8 per mine or $150.46 in 2025. Interestingly the design was published during the war for people to make mines to sell at home to sell to the government and most of the supplies for it today can be found at ACE Hardware.  . . Kind of scary to think about actually. The actual explosive (an early form of tannerite) was made from Fertilizer and Zirconium Hydroxide which can be found in Ceramics at the time.