Operation Mincemeat. It sounds like something right out of a James Bond story (or at least a spoof of a James Bond story — Our Man Flint, perhaps). But it was a real operation, conceived by Bond creator Ian Fleming when he was in the British Navy.
Glyndwr Michael, homeless, jobless, and desperate (and without a vowel in his first name), killed himself with rat poison in 1943. Thanks to an ingenious plot by Fleming, he died again, this time for king and country.
Prior to a critical World War II operation, the British took the dead man and made him up to look like a Royal Marines courier, then planted him in Spain with a fake ID and a bunch of fake “top secret” documents indicating the Allies were going to invade the Germans in Greece. It was a decoy of course. Spain was chosen because it was loaded with Nazi spies that would probably take the message to Hitler.
Thanks to the ability to decode the German Enigma machine, the Allies could observe what was happening, and the message did indeed get to Hitler. Hitler sent 90,000 men to Greece, while the Allies invaded Sicily, toppling Mussolini and turning the course of the war.
The story was told in the 1956 film with Clifton Webb, The Man Who Never Was.
It occurred to me when reading about the British use of fictitious double agents, that this must have influenced Hitchcock’s North by Northwest, where Cary Grant’s Roger Thornhill was mistaken for George Kaplan, a spy who (HUGE SPOILER ALERT) ….
turned out to not exist.
Here’s the full article about Operation Mincemeat, which was also covered in a book by Ben Macintyre and made into a BBC documentary. Hare’s another article, this one from the New York Times, on Macintyre’s book and the operation (which was originally called Operation Trojan Horse).