The SD was set up by Himmler in 1931 as the security and intelligence arm of the SS. It worked closely with the Kripo and the Gestapo and gradually took over more tasks from both these organisations.

From 1937 the SD operated within Germany as an intelligence agency, collecting information on ideological opponents and reporting on the public mood. The foreign intelligence arm of the SD, the SD-Auslandsnachrichtendienst, collected information about other countries via a web of informers.

After the outbreak of World War II and the establishment of the RSHA (Reich Main Office of Security) members of the Gestapo and the Kripo in occupied territories wore the SD vignette on their uniforms. In Amsterdam the SD headquarters were in the Euterpestraat. In The Hague the offices were situated on the Rijswijkseweg and near Westbroekpark. During the Nuremberg trials the SD was classified as a criminal organisation.

• H. Boberach, ‘Sicherheitsdienst (SD)’, in: W. Benz, H. Graml en H. Weiß ed., Enzyklopädie  des Nationalsozialismus (München 1997) 728-729.
• M. Wildt ed. Nachrichtendienst, politische Elite und Mordeinheit – Der Sicherheitsdienst des Reichsführers SS (Hamburg 2003).
• Meldungen aus dem Reich 1938 – 1945. Die geheimen Lageberichte des Sicherheitsdienstes der SS, uitgegeven door H. Boberach, Bd. 1 – 17 (Herrsching 1984)