Door: Office of Strategic Services (voorloper van oa. CIA, werkzaam gedurende Tweede Wereldoorlog).

“In hopes of shaking the morale further in the German people, the OSS called upon master forgers similar in nature as MI6 once had, but rather than having an image of Heinrich Himmler replacing Hitler, the OSS used a stamp of Hitler, but with some minor modifications. The modifications included a skull overlay that resembles a portion of Hitler’s jaw having been “eaten away”. The German subscript at the bottom of the stamp was also altered from ‘Deutsches Reich’ (German Empire) to ‘Futsches Reich’ (ruined empire). These stamps were known as the “Death Head” and were usually placed in the letter with other subversive materials.[3] The letters were arranged in Reichspost bags that the OSS had forged to resemble the original bags. These precisely made bags were indistinguishable from the real German mail bags and were mimicked down to the material used.[4] The bags would then be loaded aboard bombs specially designed to deploy the bags near a destroyed train, preferably one carrying mail, and drop the forgeries in amongst the originals in hopes that they would be put into circulation with the rest of the mail.”

Aldus wikipedia.