Black propaganda

The classic cases are the British wartime radio stations that broadcast to Germany in German. Gustav Siegfried Eins, which began in 1941, posed as the voice of a disgruntled Prussian officer; Soldatensender Calais, from 1943, posed as a German forces station and carried accurate war news, dance music, and a steady drip of demoralising detail. Sefton Delmer, the journalist who ran them, held that the stations had to be mostly true to be believed at all, and spent their credibility carefully.

That is the general rule of black propaganda. The lie is about the sender; the content is as true as it can afford to be, because the whole point is to be trusted by an audience that would not trust the real source. Forged documents, Spoofed Outlets that mimic a real newspaper's design, and Synthetic Personas that pose as local voices are black by the same logic.

Online, the line between black and gray has blurred. A troll farm's accounts claim nationalities, hometowns, and occupations they do not have, which is black; the network behind them is merely unacknowledged, which is gray. Researchers tend to describe the whole arrangement with the platform term "coordinated inauthentic behavior", which covers both.

Compare white propaganda and gray propaganda.