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"On This Date in History" Calendar

1939: Meeting of Pyry took place.....

Thursday, July 25, 2024

On 25 & 26 July 1939, one of the most important events in the history of intelligence took place in the woods outside Warsaw. Just three weeks before the Government Code and Cypher School (GC&CS) moved to its War Station at Bletchley Park, its Head, Alastair Denniston, and its Chief Cryptanalyst, Dilly Knox, traveled to Warsaw to meet their Polish and French equivalents. During this meeting, Poland shared its successes against the ENIGMA with Britain and France. Poland’s main codebreakers were Jerzy Rozycki, Henryk Zygalski, and Marian Rejewski who joined the Polish General Staff's Cipher Bureau in Warsaw. (Image is of Denniston's travel documents - via the Bletchley Park Web site.)

The first breakthroughs in regard to solving the Enigma did not occur at Bletchley Park, but rather had already occurred in Poland. German military messages enciphered on the Enigma were first broken by the Polish Cipher Bureau, beginning in December 1932. Three Polish mathematicians pioneered the solutions - Jerzy Rozycki, Henryk Zygalski and Marian Rejewski. The Poles had understood that it was necessary to use mathematics to look for patterns, and they had then taken a further step by building electro-mechanical machines to search for solutions, known as "bombas."

The GCHQ Departmental Historian said, “To the surprise of the British, the Poles, who had treated Enigma as a mathematical problem from the outset, were much further forward than they were both in terms of successful cryptanalysis and of building machinery to support cryptanalysis. The Poles were generous and shared everything they had with their allies.”

Visit the link below to learn more about the Meeting of Pyry and the 75th anniversary in 2014.

Also read the article, "Poland's Overlooked Enigma Codebreakers," by Gordon Corera for BBC News and "Polish Codebreakers 'cracked Enigma before Alan Turing'" in the Telegraph - links below.

And read, "The Hacker Who Saved Thirty Million Lives," by Wojciech Oleksiak - about Polish mathematician Marian Rejewski via the link below.


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