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

8. United States in the secret war

Between WW1 and WW2 the United States had no unified intelligence information distribution. The intercepted messages were scattered between a number of organizations and though some travelled through rapid channels of communication, some were diverted by technical or procedural delays and some never reached a centre of decision. By the end of the twenties, the US cryptoanalysis unit, named "Black Chamber", was running into trouble and could not break new codes. In May 1928 they ordered a single commercial version of the Enigma machine. Their effort was stopped by the Secretary of State, H. L. Stimson, on the principle that "gentlemen do not read each other's mail". Like a true man of honour he disbanded the "Black Chamber" but, luckily, it survived in another department.

In 1940 the USA and Britain started exchanging scientific intelligence information. The USA gave Britain information on the Japanese Purple code and Britain gave the USA information on the German Enigma code. In addition, four Americans (A. Simkov, L. Rosen, P. Currier and R. Weeks) were sent for a 5-week study at Bletchley Park. In April 1942, a conference held in Washington led to ever increasing cooperation and both US and British intelligence regularly exchanged secret information. Both the US President, F. D. Roosevelt, and Gen. D. D. Eisenhower were briefed on the benefits and the security responsibilities of ULTRA secret. US commanders were brought on board and US Army units were installed at Bletchley Park to perform interception, operate "Bombes" and to perform cryptoanalysis with major interest in the German U-boat code. The American contingent was more than 200 strong.

In September 1943 an Anglo-American agreement incorporated US personnel into the British structure. In spite of that, many US generals such as G. S. Patton, C. Spaatz, and I. Eaker did not have faith in the value of Ultra intelligence. One example of that was a tragic event on 14th October 1943 when 291 planes of the US Air Force raided heavily defended Schweinfurt and suffered very heavy casualties! This loss was due to the refusal of Gen. Eaker to take into account the strength of the German Fighter Force as predicted by Enigma intercepts. In the Battle of the Atlantic the situation was different. Throughout 1942 no Naval Enigma messages were decrypted and shipping losses were staggering. In 1942 the US Navy had no Operational Intelligence Centre and, on a British initiative, the US Navy established Atlantic Operations Intelligence. Close cooperation was assured by direct connection between the US and British Tracking Rooms. This permitted coordinated monitoring of German U-boat locations, planning of convoy routes and efficient disposition of Allied Strike Forces.

In December 1942 the German Naval Triton code was broken and shipping losses were dramatically reduced! In parallel with successful Atlantic Operations Intelligence, the US Army established its own Special Branch under the command of the Military Intelligence Service Chief, Brigadier General M. W. Clark. Until 1943 the cooperation was somewhat haphazard but it reached its peak in preparation for the invasion of the Continent. Since US commanders, unlike the British, had no experience of using Ultra, Gen. G. Marshall sent a letter to Gen. D. D. Eisenhower chartering the use of Ultra and the authority of Liaison Officers: "Their primary responsibility will be to evaluate Ultra intelligence, present it in usable form to the Commanding Officer and to such of his officers as are authorised Ultra recipients, assist in fusing Ultra with intelligence derived from other sources, and give advice in connection with Ultra intelligence in such fashion that the security of the source is not endangered."

Although the British shared all their Ultra secrets with the US they had reservations about whether junior Liaison Officers could persuade independent US Generals to operate by the book. The evaluation and distribution of Ultra information in the USA was vastly different from British practice. At the beginning of the war, the British fighting in the Battle of Britain and in the Atlantic, were interested mainly in immediate results in the fight against overwhelming enemy forces. The United States, separated from Europe by the vast space of the Atlantic Ocean, were more interested in planning ahead with massive transfers of troops, armament and supplies to Britain and then to Europe. In July 1943 a Special Branch section was set up which published daily reports. Initially these reports were sent to the Secretary of War, Chief-of-Staff, Assistant Chief of Staff and Operations and Planning Departments. Later the list was expanded to include Admiral W. D. Leahy, Roosevelt's Chief of Staff , and Admiral E. King - Commander in Chief of the US Fleet. Ultra information was used to the limit in preparing for the invasion of the Continent.

(c) 2003 A R Dabrowa