Michael Hayden, former director of the CIA and NSA, claimed while discussing the NSA’s collection of telephone-call metadata, “We kill people based on metadata,” quickly qualifying, “But that’s not what we do with this metadata.” When declining an interview about alleged U.S. cyberattacks on Iran, he sent a one-line email that read, “Don’t know what I would have to say beyond what I read in the papers.”

At Super Bowl XXXV in Tampa police used cameras and biometric face-recognition software to survey fans. The system identified nineteen subjects of outstanding warrants, far more than anticipated. None were arrested. “We thought we were ready to use it,” said a detective.

In 480 BC, with the Persian army on the cusp of defeating Greece, Athenian general Themistocles sent a trusted slave to convey a message to Persian king Xerxes; the note professed allegiance to Persia and reported many Greek ships prepared to defect. The Persians, acting hastily on this false intelligence, sailed into the Strait of Salamis, where the Greek fleet was waiting and gained a decisive victory. 

New York Giants pitcher Christy Mathewson wrote in 1912 that he had heard the Philadelphia Athletics “had a spy” who stole signs and “tipped the batters by raising and lowering an awning a trifle.” In Philadelphia for the World Series the year before, Mathewson had looked for the culprit. “In the enemy’s camp, I kept watching the windows of the houses just outside the park for suspicious movements,” he wrote. “But I never discovered anything wrong.”

“Secretary Morrice did this day in the House, when they talked of intelligence, say that he was allowed but £700 a year,” wrote Samuel Pepys in his diary in 1668, “whereas, in Cromwell’s time, he did allow £70,000 a year for it; and was confirmed therein by Colonel Birch, who said that thereby Cromwell carried the secrets of all the princes of Europe at his girdle.”