Early in 1944 German Intelligence was piecing together evidence of a huge army in southeastern England. Reconnaissance planes brought back photographs of barracks and airflelds and fleets of ships in the Wash; General George S. Patton was seen in his unmistakable pink jodhpurs walking his white bulldog; there were bursts of wireless activity, signals between regiments in the area, confirming signs were reported by German spies in Britain.
There was no army, of course. The ships were rubber-and-timber fakes, the barracks no more real than a movie set; Patton did not have a single man under his command; the radio signals were meaningless; the spies were double agents.
The object was to fool the enemy into preparing for an invasion via the Pas de Calais, so that on D-Day the Normandy assault would have the advantage of surprise.
It was a huge, near-impossible deception. Literally thousands of people were involved in perpetrating the trick. It would have been a miracle if none of Hitler's spies ever got to know about it.
Were there any spies? At the time people thought they were surrounded by what were then called Fifth Columnists. After the war a myth grew up that MI5 had rounded up the lot by Christmas 1939. The truth seems to be that there were very few; MI5 did capture nearly all of them.
But it only needs one...
It is known that the Germans saw the signs they were meant to see in East Anglia. It is also known that they suspected a trick, and that they tried very hard to discover the truth.
That much is history. What follows is fiction.
Still and all, one suspects something like this must have happened.
"The Germans were almost completely deceived, only Hitler guessed right, and he hesitated to back his hunch..."
A. J. P. Taylor,
English History 1914-1945