"On This Date in History" Calendar
1586: Mary, Queen of Scots, sent treasonous coded response to the Babington Letter.
17 July 1586: Mary, Queen of Scots, sent a treasonous response to the Babington Letter. Pictured here is the cipher code used by Mary, Queen of Scots - image via Wikipedia. On 8 February 1587, she was executed for treason, as a result of a solution of a cryptosystem she was using in a conspiracy to assassinate Queen Elizabeth (Babington Plot).