Breaking the Enigma code
Polish contribution to victory

Andrzej Dabrowa, Ph.D.

Enigma machine M Rajewski H Zygalski J. Rozycki
Chapters
  1. Synopsis
  2. Historical background
  3. Breaking the Enigma Code
  4. Polish decrypting effort 1930-1939
  5. Polish decrypting effort 1939-1945
  6. English decrypting effort - the beginnings
  7. England - Bletchley Park
  8. United States in the secret war
  9. Battle of Britain
  10. British northeast Africa
  11. Invasion of French northwest Africa
  12. Battle of the Atlantic
  13. Battle of the terror weapons V1 & V2
  14. German atrocities
  15. Enigma security
  16. Conclusion
  17. Epilogue
  18. Glossary and abbreviations
  19. References

6. British decrypting effort - the beginnings

In the second half of the thirties Germany's investment in the war machine was much greater than that of the major opposing powers, France and Britain. In the five years from 1935 to 1939, German military expenditure was estimated to be $23,900,000,000 compared to a total expenditure of $11,705,000,000 for Poland, France and England together. The German Air Force was perfecting its tactics in war-torn Spain and was pushing ahead with the design of modern aircraft. The Navy, realising that the war with England would be fought in the Atlantic, was pushing ahead with the design and construction of a large modern submarine fleet.

In response France, using WW1 trench warfare mentality, was modernising its Maginot Line - not realising that future wars would be highly mobile. Britain was still the largest economic empire in the world but, due to fiscal constraints, its Navy consisted mainly of WW1-vintage ships that would be ill equipped to wage war against a German U-boat fleet in the Atlantic. The Air Force realising that it had no aircraft that could hit military industrial complex targets deep in Germany, a major requirement in a war, was establishing an ambitious plan firstly to defend Britain and then to strike back deep into Germany.

In 1939 the German forces employed more than 4,500 cryptologists while Britain, France and Poland employed only 200, 130 and 60 respectively. Realizing that war was imminent, in the spring of 1939 a small group of less than 30 people in the Signal Intelligence Service (SIS) started working seriously. Their most immediate and important task was to recruit suitable personnel in the fields of intelligence, mathematics, cryptology and German language and history.

Bletchley Park
In September 1939 SIS was evacuated to a new location at Bletchley Park, located 45 miles northwest of London. As a result of the Polish achievements the British possessed a method for breaking the Enigma cipher and the military version of the Enigma machine made by the Poles. This gave them a tremendous start in decrypting the early messages but, as shown by the experience of the Polish cryptologists, their success also depended on poor operational procedures and mistakes made by the German operators.

(c) 2003 A R Dabrowa