In 1941, English code breakers at Bletchley Park learned that the massive German battleship Bismarck had left the Baltic, on course to attack vital Allied shipping in the Atlantic. British battleships were then able to intercept and ultimately sink the dreaded Bismarck. Three hundred and fifty-three years earlier, code breakers working for Queen Elizabeth’s principal secretary, Sir Francis Walsingham, kept him apprised of the whereabouts of 130 ships well enough for him to dispatch Sir Francis Drake’s vessels to intercept and defeat the Spanish Armada. As Stephen Budiansky writes in Her Majesty’s Spymaster, Walsingham also established a modern, professional spy network throughout the courts of Europe. Walsingham had a task juicier than anything Bletchley Park ever worked on, though. His ability to decode Mary of Scotland’s letters proved her treason and sealed her fate. Hear Budiansky trace the history of modern espionage and Walsingham—that’s Walsingham, Francis Walsingham’s—role when he reads at noon at the International Spy Museum, 800 F St. NW. Free. (202) 393-7798. (Janet Hopf)