I was reading up on the disinformation campaign by the Allies before and after the invasion of Normandy. The Allies knew the Germans expected an invasion, but we made tremendous efforts to convince the enemy that the invasion would occur near Calais, almost 200 miles away from the actual intended landing area, as well as attempting to create the impression that the actual invasion was merely a feint.
These particular disinformation projects were called Fortitude North and Fortitude South. Fortitude North was intended to convince the Nazis that the Allies would invade through Norway.
Fortitude South included such subterfuges as sending General George Patton to the point in England opposite Calais, and behaving as if he were forming an army there.
That involved feeding the Nazis false information by fake radio messages back and forth from fake Army units, emplacing dummy tanks, landing craft, and airplanes in the area, etc. And of course, General Patton was expected to be visibly traveling around the area to "organize" this fake Army.
But one of the unique aspects of this affair was having a spy, code-named "GARBO," feed the Nazis false information. This was so effective that GARBO established a fake sub-network of imaginary spies, for which the Germans were paying salaries and travel expenses through him.
GARBO was so successful in duping the Germans that toward the end of the war, he was awarded the German Iron Cross.
Oh, and incidentally, the British also rewarded him by making him a Member of the Order of the British Empire, another high honor. He was thus awarded high medals from both warring parties --a pretty rare thing.
His story is fascinating, full of duplicitous machinations and clever ruses to convince the Germans of his loyalty and effectiveness as a spy.
Enjoy:
http://en.wikipedia.org/wiki/Joan_Pujol_GarciaTerry
More: ("Fortitude"):
http://en.wikipedia.org/wiki/Operation_FortitudeCf. also Stephen E. Ambrose,
D-DAY June 6 1944: The climactic battle of World War II, Chapter 4, pp 71ff.