John Pryor was a naval officer aboard one of the ships which, under German bombardment, had already rescued one load of troops. When it went back for a second load, the ship ran aground and Pryor was captured. He spent the rest of the war in a German POW camp from which he wrote dozens of letters back to his family in England.
Stephen Pryor says his father's letters were always considered special, but that his grandfather, to whom they were addressed, didn't know how special.
CBS News' Mark Phillips asked Stephen Pryor, "Did you always know that contained within in these letters was some sort of secret code?"
http://www.cbsnews.com/8301-505263_...hin-wwii-pows-letters-cracked-70-years-later/