NPR had a great segment tonight on Juan Pujol Garcia, a double agent working for the British during World War II. He was the one who persuaded the Germans that the planned D-Day invasion of Normandy was merely a feint and that the real attack would come at Calais.

It started out pretty unpropitiously. A thirty-two-year-old failed chicken farmer and manager of a one-star hotel, he presented himself at the British embassy and offered his services as a spy, but they laughed him off, as he had no experience. So, to get experience, and to make himself worth something to the British, he went to Germany and said he he'd spy for them, showing them a forged British diplomatic passport that was good enough to fool them. So, they said, okay, and sent him to London--but he couldn't get to London, so he went to Lisbon, instead.

He had never actually been to London and didn't speak English. Nevertheless, he made up false dispatches about things going on London, based on newsreels he'd see in the theater. The Nazis believed him--in fact, his fabrications were so believable that British counterintelligence launched a manhunt for him in London. When the British saw how his (false) story of a planned attack on Malta spurred the Nazis to move ships to intercept this attack, they smuggled him into England, and gave him the code name Garbo.

There you have it: writing what he didn't know! (Story here: "'Agent Garbo,' The Spy Who Lied about D-Day")

P.S. He's probably the only spy to receive both an iron cross, from the Germans, and, five months later, an MBE from the British.