Sub Lieutenant John Pryor Sent Coded Letters Home From A German POW Camp Passing Scads Of Valuable Intelligence.

by Daniel Russ on June 21, 2013


John Pryor Posing Among British POWs Taken At Dunkirk




.MI9 created an elaborate and game based code to communicate with POWs the details of their condition, and whatever details they had about the state of the enemy. It was complex. It was done manually, not with sophisticated hand cranked computational devices that the Germans were using for their encryption. When a letter came into Britain from a German POW camp, it came with an indicator that it contained a code. For example, if the letter was addressed 22 March 1942, it was just a letter. If it was dated in the continental method, 22/3/42, this indicated it contained a message.


The messages were hidden by carefully choosing the forth or fifth word. Decoders had a complex method of creating a 12 by 12 grid, laying the letters out on both axis in the grid. Numerical letter equivalents would hide another level of complexity with them.


The Daily Mail has a magnificent example of a letter that asked for passports and clothes and maps of the Swiss border to help prisoners escape. In another, Submarine Lieutenant John Pryor sent a coded message about the sinking of the HMS Undine, a British sub.


“Sub Lt Pryor was captured at Dunkirk in 1940 and sent to a prisoner of war camp.  He was held for the next five years but as a reward for good behaviour, he was allowed to send letters home to his parents in Saltash, Cornwall.

Those letters contained secret messages for the British military – and involved a fiendishly complex alphanumeric code. In one letter, he hid intelligence about the sinking of a British submarine by writing about the PoW camp’s vegetable garden. He wrote: ‘Many seeds are left, being saved from several plants which did very well some time ago. ‘Our last year’s harvest was extremely good. Well worth repeating again for this year.’ But it meant: ‘HMS Undine attack failure. Trawler depth-charged, scuttled in 70 feet, three burnt.’ From this, experts were able to deduce a coded message about the sinking of the British submarine, the HMS Undine, which was destroyed in 1940.”




       Letter From Sub Lieutenant John Pryor Is Loaded With Coded Info




                    Code Breaking Chart For POW Letters Home





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