How Enigma Was Broken: Newly Found Letters Detail Interception of Its Prototype

Newly unearthed correspondence between Polish cryptologists Marian Rejewski and Leonard S. Danilewicz offers fresh insights into the breaking of the Enigma code. The letters, discovered by Polish-born researcher Tomasz Muskus in London, were initiated by Rejewski in 1974.

“

This correspondence is in London with the son of Leonard S. Danilewicz. It was not widely known to historians, nor was it published. Perhaps it will be transferred to one of the Polish museums.

Rejewski, a renowned mathematician and cryptologist, began writing to Danilewicz, a co-owner of the AVA Radio Manufacturing Works, after French General Gustave Bertrand published his memoirs in 1973. Bertrand's account revealed the secret of the Enigma machine's decryption and highlighted the role of Poland's Cipher Bureau. Rejewski aimed to ensure the Polish contribution was accurately represented, as he felt it was being omitted from British publications.

In his letters, Rejewski expressed concern that British books on the subject, such as F.W. Winterbotham's "The Ultra Secret," might not fully capture the Polish effort. He noted the passing of key figures like Langer, Ciężki, Palluth, and Fokczyński, leaving few competent individuals to provide firsthand accounts. Rejewski himself had written an extensive memoir in 1967, but it focused on the scientific aspects of the enigma.

“

At the end of this year, a book by F.W. Winterbotham titled 'The Ultra Secret' was published in Great Britain. Presumably, a Polish book on the same topic will be released next year. It is understandable that the Polish book should be the most accurate, most complete, and best-documented of all. However, the difficulty lies in the fact that very few competent individuals remain alive.

Rejewski specifically sought Danilewicz's input regarding the AVA works, which produced vital equipment for the Cipher Bureau, including the "bombs" (Rejewski machines) used for decryption and replicas of the Enigma machine itself. He also inquired about the Polish military cipher machine, Lacida. As Danilewicz was the sole surviving partner of AVA, Rejewski considered his testimony crucial for a comprehensive and well-documented account of the Polish success in breaking Enigma's code.

“

And since you were one of the four partners of 'Ava,' let me add: 'the only one still alive,' hence my current letter, as I am trying to provide the author of the future book with as much material as possible.