The Secret Code of Mary Queen of Scots

In 1586 Elizabeth spies used that prominent E to solve the secret code Mary Queen of Scots was using. The messages revealed a plot by Babington and six unnamed members of Elizabeth's court. With the plot revealed, Walsingham and his fellow spymasters began to investigate the persons who might be involved. And after a bit of trial and error they were eventually able to decipher the code, and the contents of each message.