The Hidden Truth: Why the British Initially Kept the BOMBE Machine Secret from Their American Allies During WWII

During World War II, the British and Americans engaged in a crucial race to decipher secret messages, a race that would ultimately determine the outcome of the war. Yet, it was not without its mysteries and strategic considerations. A lesser-known detail in this historical saga involves the British Government's decision to initially withhold the BOMBE machine from their American allies, even before the United States formally joined the war effort. This article delves into the reasons behind this strategic move and how it impacted the breakthroughs in cryptography and intelligence-gathering efforts.

Early Exchanges and the Arrival of American Cryptographers at Bletchley Park

On January 25, 1940, history took a significant turn when the Royal Navy battleship King George V departed from Annapolis Roads, bringing a delegation of US cryptographers to Bletchley Park. This momentous event occurred more than eleven months before the infamous attack on Pearl Harbor that drew the United States into the war. The US delegation, which included Abraham Sinkov, Leo Rosen, Lt. Prescott Currier, and Lt. Robert Weeks, brought with them invaluable knowledge and resources, including a working Japanese Purple encoding machine and crates of intelligence papers.

These cryptographers arrived in an environment rich with cutting-edge technology and intelligence. They were introduced to the latest techniques in breaking Enigma codes, the Bletchley Park Bombes, signals interception, and intelligence collection offices. The visit extended for five weeks, during which the American team was fully immersed in the operations of Bletchley Park. Notably, they tutored the British team on how to break the Japanese Purple code, a critical breakthrough that contributed significantly to the war effort.

Strategic Decisions and Security Concerns

Despite the significant value the US delegation brought to Bletchley Park, there was a strategic consideration behind the British decision to initially withhold the BOMBE machine from their American allies. The main reason lay in security concerns. The British intelligence community was deeply worried that the Germans might discover that the Enigma machine, which they believed to be unbreakable, was not as secure as they thought. This anxiety was not without merit, as intelligence leaks were a real risk in an era of cautious military operations.

The Bletchley Park team meticulously shared its expertise with the US delegation, but the decision to withhold the BOMBE machine itself was a calculated risk. By postponing the dissemination of this crucial technology, the British aimed to maintain a significant advantage in the race to decipher German communications. It was only in late 1942, when the British encountered production problems with their BOMBES, that they had to share the relevant information with the Americans, enabling them to build their own.

Collaborative Efforts and Final Integration

The eventual integration of the Bletchley Park efforts with the American OP-20-G was a positive outcome that served both sides. By 1943, Bletchley Park and OP-20-G were fully integrated, sharing the daily workload of breaking Enigma machine settings. However, the impact of American bombing was particularly significant. Joe Desch, an often overlooked figure in the story, developed significant improvements to the original British Bombe at National Cash Register. The US-produced bombes were not only faster but also more reliable. By December 1943, 120 machines were operational in the US, significantly increasing the ability to break German Naval Enigma traffic.

Conclusion

The decision by the British to initially hide the BOMBE machine from their American allies during World War II was a strategic move rooted in security concerns and the inherent risks of intelligence leaks. Despite the initial secrecy, the eventual collaboration between Bletchley Park and the American efforts proved to be a turning point in the war, significantly enhancing the Allies' ability to decrypt German messages. This episode of history not only sheds light on the complexities of military intelligence operations but also underscores the importance of trust and collaboration in overcoming shared challenges.