Fascinating episode. The Brits were nonpareil in their use of deception, and this may be the best-known example.
It's the Spring of 1943. The Allies have the North African coast under control now and they're next step is to invade the European continent. The obvious pathway is through Sicily at the toe of the Italian boot. But the Germans know this and have deployed many units to Sicily to bolster the Italian troops. Was it possible to trick the Germans into believing that the landings would take place somewhere other than Sicily? Well, yes it was. The task was given to Ewan Montague, an intelligence officer, who got hold of an anonymous corpse, gave him the identity of a Major Martin in the Royal Marines, and dumped him off the coast of Spain with a briefcase full of (fake) top secret information about the landings chained to his wrist.
The body was recovered by the Spanish, the papers examined by the Germans, and resistance to the landings on Sicily was lessened, saving many lives.
But many people already know about "Operation Mincemeat." Montagues' post-war book, "The Man Who Never Was," became a best seller. A feature film starring Clifton Webb was a success.
But mystery still surrounds the identity of the person who was the real body set afloat off Huelva. Montague never revealed it. In 1997 it was claimed that the body was that of a Welsh vagrant who had died of pneumonia, but the explanation leaves several loose ends that the film explores. The tentative conclusion is that the body wasn't that of a Welshman at all, but that of a sailor who had drowned when his ship exploded while entering a British port.
The links provided fit the argument but that proves nothing. The viewer can judge for himself.