Office of Strategic Services (OSS)
American intelligence organization
The Office of Strategic Services (or OSS) was the precursor to the modern Central Intelligence Agency tasked with intelligence collection and paramilitary operations. OSS ran operations throughout occupied France. Their work was critical in laying the groundwork for the D-Day invasion in June of 1944.
German secret police
The Sicherheitsdienst (SD) was a branch of the Gestapo which operated in occupied France during WWII. The SD’s tenure in France was brutal, and their treatment of allied spies was even worse.
German radio intelligence
The Funkabwehr was a radio intelligence service tasked with finding clandestine radio signals being used by the French population. Using radio direction finding (DF) methods, their activities posed a great risk to allied intelligence operations. Trucks bearing radio interception technologies could be seen on the streets of Paris searching for hidden spies.