So I'm browsing through Alibris for books on "prisoner rehabilitation," and what do I come across but yet more christmas cheer:
Single sheet of stout card measuring approx. 4.5 x 7.5 inches (12.0 x 19.0 cms), obverse with gilt edges printed with the insignia of 'Admiral Inspector of the Fleet' in gilt and black and seasonal text in black; reverse blank. The seasonal text, SIGNED BY DONITZ IN BLUE INK, reads 'Grossadmiral Donitz dankt fur die guten Wunsche zum Weihachtsfest und zum neuen jahr und erwidert sie herzlich'. Grossadmiral Karl Donitz (1871-1980), German naval leader and Hitler's successor, commanded the Kriegsmarine during the latter half of WWII and is remembered particularly for his promotion of the U-boat offensive.
I suppose you could call Doenitz a rehabilitated (de-nazified) prisoner (of war). The card is yours for only $929.61!