1944 (8 Jan) German Occupation, Germany, Cesored Postcard from Jägern to Portugal, German and Portugeese Censorship Postmark, Chemically examined for Invisible Ink

This is a rare and significant World War II postal document dated January 8, 1944 showcasing the direct intersection of civilian life, military censorship, and counter-espionage in occupied Europe.
Written in Polish by Maria Nalezińska from Schönwald (located in the Warthegau, a region of occupied Poland annexed by Nazi Germany), the text is a seemingly ordinary family update.

Despite its innocent tone, the postcard triggered intense security protocols as it traveled from occupied Poland to neutral Lisbon, Portugal

The front features the official eagle-and-swastika transit stamp of the Oberkommando der Wehrmacht (OKW), the German High Command responsible for inspecting all foreign mail.
Upon arrival in Lisbon—a major diplomatic and intelligence hub during the war—the card was processed and stamped by the Portuguese censorship authority (3ª Secção).

The prominent, sweeping blue/purple streak across the Polish text on the back is physical proof of wartime chemical censorship. German or Allied postal inspectors swiped the card with chemical indicator solutions (such as iodine or iron compounds) to detect hidden text written in invisible or "sympathetic" ink, a common practice used to intercept covert intelligence.

Provenance: Ex Werbizky.