The Prussian Secret Police (German: Preußische Geheimpolizei) was the secret police of the Prussia in the 19th and early 20th centuries. In 1851 the Police Union of German States was set up by the police forces of Austria, Prussia, Bavaria, Saxony, Hanover, Baden, and Württemberg (Deflem 1996). It was specifically organised to suppress political dissent in the wake of the 1848 revolutions which spread across Germany. For the next fifteen years the Union held annual meetings to exchange information. Source: Wikipedia (en)