James Madison (1751–1836), the fourth President of the United States, left behind an enormous documentary legacy.

In his book The Agony Column Codes & Ciphers, codebreaker Tony Gaffney presents more than a thousand encrypted newspaper advertisements from Victorian England.

Today, we are once again looking at a postcard – one that was kindly made available to me by Edmond Kern.

At the HistoCrypt 2026, I came across an encrypted document, which was exhibited by French radio history expert Didier Clarençon.

At HistoCrypt 2026 in Amiens, French collector Edmond Kern presented his remarkable collection of historical cryptographic material. Besides a number of cipher devices, the collection includes many encrypted postcards. I am very grateful to Edmond for allowing me to feature these fascinating items on my blog. Today I am starting with the first postcard, and I expect several more will follow.