[SunkenCiv]

Thanks Ultra Sonic 007, I'm going to add this, probably not ping though. :')

persuading Nazi spies to become double agents was vital to the success of the D-Day landings and deceiving the German army about where Britain planned to attack from.

That was easy -- Britain would attack from Greece and Italy, until Stalin humiliated Churchill at one of the wartime "Big Three" conferences and demanded that the US plan for the cross-channel invasion be allowed to go forward. Churchill still got his way after D-Day by making sure that the do-nothing Montgomery had priority of supply.

Operation Double Cross is dressed up a bit here for the modern audience -- the Abwehr spies were caught, given the option of either hanging or turning coat, and those who didn't hang not only relayed harmless real info along with complete fabrications, but also convinced more Abwehr spies to come over, and those spies were also apprehended immediately and given the same stark choice. This preponderance of phony evidence kept German reinforcements tied up at the Pas de Calais while more and more allied forces landed at Normandy.

Thanks again, US007.

[Paisan]

given the option of either hanging or turning coat, and those who didn’t hang not only relayed harmless real info along with complete fabrications

Yes, this was my understanding as well. When German V-2 rockets were raining down on England, these ‘turned’ spies radioed back to their handlers the location of the impact. When the rockets missed by miles, their message was that the rockets were right on target.