Swiss Postal History Reveals How Wartime Censors Systematically Violated Private Correspondence to Protect National Security

Historical records from the Swiss National Museum detail the chemical and physical methods used by censors to monitor private mail during the world wars.

By: AXL Media

Published: Apr 17, 2026, 4:05 PM EDT

Source: The information in this article was sourced from SWI swissinfo.ch

The Fragility of Constitutional Privacy in Times of Crisis

The fundamental right to privacy in Switzerland, currently protected under Article 13 of the Federal Constitution, has historically proven susceptible to suspension during periods of geopolitical upheaval. While modern law strictly forbids the opening or investigation of mail without explicit judicial authorization, the two world wars established a precedent where national security took precedence over personal confidentiality. During the First World War, postal workers were regularly instructed to intercept correspondence deemed insulting to foreign monarchs or statesmen to preserve Swiss neutrality. This early form of state surveillance demonstrated that the sanctity of the envelope was conditional, depending largely on the political stability of the European continent.

State Propaganda and the Policing of Subversive Speech

As the Second World War approached in 1938, the Swiss government intensified its efforts to control the flow of information by targeting propaganda viewed as a threat to the state. Military and police units were granted broad authority to monitor the telegrams, phone calls, and letters of individuals suspected of undermining national safety. Although the Federal Council held the exclusive power to impose general censorship, the lack of specific operational guidelines meant that surveillance was often conducted with broad discretion. This systemic monitoring was designed to identify internal dissent and prevent the infiltration of foreign ideologies that could compromise the nation’s precarious position as a neutral enclave.

The Overt Psychological Tactics of Foreign Censors

While Swiss internal monitoring was selective, international mail leaving or entering the country faced a much more aggressive and transparent form of surveillance by belligerent nations. Postal authorities in Germany and France made no effort to hide their intrusions, frequently resealing opened envelopes with adhesive tape and official stamps. This was a deliberate psychological strategy intended to remind the public that their private thoughts were being scrutinized by the state. The personal archives of individuals like Helene von Wild, a Swiss citizen living between Bern and Barcelona, provide clear evidence of these practices, featuring envelopes prominently marked by censors in Munich and Spain....