Code-breaking began as a hobby for the French infantryman, who impressed his peers deciphering secret messages between lovers in local newspapers. In 1891, the authorities brought Bazeries in to revamp the cylinder cipher for the military. He went on to help crack German codes during WWI. But he is most famous for spending three years cracking the "Great Cipher," created by Antoine Rossignol for King Louis XIV, which concealed information about the Man in the Iron Mask. The devious cipher included codes meant to erase words decoded earlier in the text.