As a prisoner of war, Sub Lieut. John Pryor encrypted information and requests for supplies in letters sent from a German camp to his family in Cornwall.
It's been 70 years since the letters of John Pryor were understood in their full meaning. That's because as a British prisoner of war in Nazi Germany, Pryor's letters home to his family also included intricate codes that were recently deciphered for the first time since the 1940s.
Pryor's letters served their purpose in World War II, as Britain's MI9 agents decoded the messages hidden within them — requests for supplies, notes about German activities — before sending them along to Pryor's family in Cornwall.
"There were two types of information buried in these letters," Pryor's son, Stephen, . "There is military intelligence going back about munitions dumps, about submarines that have been sunk, and information requests for British Military Intelligence in London to send maps and German currency and German ID, to help them with their escape plans."
For the rest of the story: http://www.npr.org/blogs/thetwo-way/2013/05/04/181104605/world-war-ii-code-is-broken-decades-after-pow-used-it