Britain’s Salvation: Cryptography at Bletchly Park

Britain's Salvation:

Cryptography at Bletchley Park

In the beginning of World War II, Britain set up an intelligence agency on the outskirts of London to be used as the center of intelligence operations during Britain's battle against Germany. The agency consisted of a group of small houses, dubbed "huts", within a large estate called Bletchley Park (Kahn 32). Here Britain's best scientists, teachers, chess champions and other great minds stayed for the majority of the war obtaining information that would help Britain win (Hinsley 4). The main focus of Bletchley Park was cryptography, the decryption of enemy transmissions. In the beginning of the war a new encoding system had been developed by Germany making it nearly impossible for Britain to decrypt intercepted messages. Using new technology and Britain's greatest minds, Britain was able to decode messages from the Germans, Japanese, and Italians. This breakthrough eventually led to the defeat of Germany in World War II. Though many people may contend that Bletchley Park did not significantly aid the British in defeating Germany, it in fact contributed greatly in obtaining information that eventually lead to Britain's victory of Germany. The contributions made by those at Bletchley Park in cryptography significantly aided the British in their defeat of Germany in World War II.

At the very beginning of the war, Germany developed a new encrypting system that perplexed British cryptographers for more than a year. It was known as the Enigma. Using a combination of three rotating wheels and changing the order of these wheels daily made it nearly impossible for the British cryptographers to decipher. The code changed every day and none of the intercepted messages were longer than a couple hundred letters (Sebag-Montefiore 57). Since the wheels rotated slightly for each character that was typed, the code had over 17,500 different codes on a given day. Because the code did not repeat until the 17576th character, it made it more difficult for the allies to recognize any patterns in the transmissions (Hinsley 94). Without being able to decode the encryption system, Britain and their allies were unable to learn about the movements of the German troops and submarines or U-boats. As the beginning of the war progressed, the number of British convoys that were being sunk by German U-boats increased drastically. Finally, when it looked like Germany would overtake Britain, England was able to obtain the codes for the Enigma.

In April of 1941, the British obtained these codes when a British destroyer, the Bulldog was attacked by a German U-110, a type of submarine. The Bulldog was able to disable the U-110 using depth charges. The crew of the U-110 abandoned the submarine leaving it to sink and thus destroy the Enigma and codebooks that were on board (Kahn 21-22). However, Crewmembers of the Bulldog were able to board the U-110 and obtain the Enigma and corresponding codebooks for the next month. This gave British cryptographers at Bletchley Park the edge that they needed to help determine Germany's encryption system. It also allowed England and their allies to begin to retaliate against the Germans. After determining the encryption system, Britain was then able to decode any transmissions that Germany encrypted using the Enigma. Germany never learned about their breach in security and they did not know that Britain had the Enigma until the information was finally released in the 1970's (Sebag-Montefiore 165). As a result of obtaining the Enigma, Britain was able to take the offensive.

With the knowledge of the German's codes, Britain was able to begin launching an offensive of their own. They began to win more battles and fewer British convoys were sunk due to the intelligence gained from the British cryptographers at Bletchley Park. The cryptographers were able to intercept transmissions of U-boat movement and warn the convoys nearby to change their path to avoid them. As the war progressed, Germany produced more U-boats making it nearly impossible for Britain and their allies to avoid them. However, with the knowledge of the U-boat's approximate location, the allies were now able to launch attacks on the U-boats, destroying Germany's only effective sea weapon. Using the knowledge of the people at Bletchley Park, the British also began to win more battles frequently halting Germany's advance. In the Mediterranean they won the battle of Matapan, destroying Germany's control in that area (Hinsley 62). They were also able to halt Rommel's advance in North