Nacht Und Nebel

Nacht und Nebel (German for "Night and Fog" — a direct reference to a "Tarnhelm" spell, from Wagner's Rheingold) was a directive (German: Erlass) of Adolf Hitler on 7 December 1941 that was originally intended to winnow out all political activists and resistance 'helpers', “anyone endangering German security” (die deutsche Sicherheit gefährden) throughout Nazi Germany's occupied territories. Two months later Armed Forces High Command Feldmarschall Wilhelm Keitel expanded it to include all persons in occupied countries who had been taken into custody and were still alive eight days later. The decree was meant to intimidate local populations into submission by denying friends and families of the missing any knowledge of their whereabouts or their fate. The prisoners were secretly transported to Germany, vanishing without a trace. In 1945, the seized Sicherheitsdienst (SD) records were found to include merely names and the initials NN (Nacht und Nebel); even the sites of graves were unchronicled. To this day, it is not known how many thousands of people disappeared as a result of this order.

The International Military Tribunal at Nuremberg held that the disappearances committed as part of the Nacht und Nebel program were war crimes which violated both the Hague Conventions and customary international law.