top of page

“My name was familiar to Military Attachés all over the world, for all mail leaving Washington concerning codes and ciphers and secret inks bore my signature.” (Herbert O. Yardley in, The American Black Chamber, p.210)

The American Patriot: An American's European Adventure

  • Later in that month of August 1918, Yardley was commissioned to London with the purpose of arranging conferences between Colonel French of the British War Office, Ambassador Page,  and Colonel Tolbert, the American Naval Attaché. During his sojourn in London, he spent much time conversing with officials and getting acquainted with the employees that worked at the American embassy in England.  It was through his interactions with those officials  that he came across a colossal problem. When Yardley requested the American code book to report his arrival to Washington, it was a young British boy that presented the book.  In his novel, Yardley expressed his shock and worries over this revelation:


    • ​I was dumbfounded when he actually opened the vaults and handed me a code book, a book that had taken months of labor and thousands of dollars of the government’s money to compile and publish…I was at a distinct disadvantage for I did not dare communicate with Washington, since the British would code every word I sent. Not having anticipated that I should find a British subject in possession of our secret codes, I had brought with me no special means of enciphering my cablegrams. (Page 211-212)

London, Great Britain

After this revelation, Yardley decided to remain in London and discover a way to rectify this dilemma. After an unknown amount of time, Yardley found a way to alert his officials back home of the problem occurring in the London embassy. After much contemplation , Yardley discovered a way to contact his superiors in Washington, despite the security breach that had taken place in London. If he first encode the message in the Military Attaché’s code book, then in some manner mutilate these letters in a method that Washington could encode, the message would be safe. Therefore, using his self-taught ciphering expertise, Yardley managed to detect and solve a problem that affected United States’ security.

Trusting that his fellow co-worker, Captain Manly, had the ability to decipher his code, Yardley submitted his telegram to the MI-8 War College office in Washington.  In this telegram, he described the current situation at the office, stating his belief that as long as the British had access to U.S secret means of communication, nothing could prevent them from enciphering and reading their messages. Ultimately, if negotiations were ever to take place between the U.S and Britain, the U.S would had no secret weapon to converse with one another. In the end, Yardley's time 's time in England was immensely beneficial for the United States.  Through his visits in British cable offices, Yardley found out that Britain had access to every telegram that passed over their cables, which they owned many of. Ultimately, it was Yardley sojourn in England that made him realize the importance of a cryptographic bureau in the United States, and it was his success there that  instigated his visit to the Cipher Bureau at British General Headquarters in France. ​​


Although the French were more cooperative than the British, they were set on never giving Yardley access to La Chambre Noir.Still, in an attempt to bypass such obstacles, Yardley recruited the help a french ally, by asking him to write a letter requesting the French government to give him access to their cipher bureau.

French Version of the Letter

Although the letters above facilitated Yardley's access into La Chambre Noir, it was his acqaintance with Colonel Cartier and its resultant friendship with Captain George Painvin that helped him succeed in France. Yardley's quick friendship with George Painvin's gave him access to the files of La Chambre Noir.  

In the end, Yardley’s experiences while in England and France served instrumental for the United States for the soon approaching Armament Conference.

bottom of page