During the French Revolution, Queen of France Marie-Antoinette sent a number of encrypted letters to Swedish diplomat Axel von Fersen. Two French scientists took a close look at them.
Marie-Antoinette (1755–1793) was a daughter of Austrian Queen Maria Theresia. In the age of 15, she was married to the French Dauphin and later became Queen of France. During the French Revolution, the royal family was placed under serious guard. Nevertheless, Marie-Antoinette succeeded in sending letters to Axel von Fersen, a Swedish diplomat living in Paris. Some of these letters were enciphered; others were plaintext or written with invisible ink.
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