A permanent exhibition that tells the story of the Bombe machines in the actual location that housed the machines which broke Enigma.
Hut 11A: The Bombe Breakthrough explains in detail the challenges posed by Enigma and explores how Alan Turing, Gordon Welchman and others devised a machine to help solve it. Using the museum’s Oral History archive and historic objects, it also considers how this contribution to the success of Allied signals intelligence had a significant impact on the course of WW2.
Wartime objects on display include original blueprints and components, decrypted Nazi messages and the W.R.N.S visitors’ book signed by key figures in the Bletchley Park story, including the GPO engineer Tommy Flowers. Some of the documents in the exhibition have never been seen by the public before. Huts 11 and 11A were amongst several wartime buildings that housed Bombe machines, but they are the only ones located within the Bletchley Park site.
These Alan Turing-designed devices changed the course of the Second World War, saving millions of lives in the process. Here is everything you need to know about the Bombes…
1. Why were the Bombes needed?
Bletchley Park was set up to decode intercepted Nazi messages, some of which had been encrypted using Engima machines. These devices typically changed settings every 24 hours and with up to 60 septillion possible combinations every day depending on Enigma model, the staff at Bletchley Park worked around the clock to break the settings by hand. A mechanical method for identifying the keys was needed and Alan Turing designed the Bombe to speed up the process.
2. How did the Bombes work and who operated them?
Enigma machines featured a set of rotors, as well as a plugboard, which helped create the millions of different settings. The electronic Bombe machines featured multiple drums representing these rotors, allowing for potential settings to be quickly checked. Hundreds of the machines were operated by Wrens. It was said to be boring and oppressive work, with the women running the machines during long shifts in dark, stuffy rooms.
3. Where were the Bombes located at Bletchley Park?
Huts 11, 11A and 11B were the home of Bombe operations at Bletchley Park. The very first machines produced were delivered to Hut 1 but, once the prototype Bombes were fully operational, more space was required. Hut 11 was built first, housing up to six machines from March 1941. Hut 11A replaced Hut 11 in February 1942, housing up to nine machines. It also contained the Bombe Control Room (this later moved to Hut 3, renamed Hut 23 in 1943). Hut 11B, a long timber-built hut to the south of Hut 11A, was used for training Wren Bombe Operators. Now demolished, its foundations have been exposed as part of the new exhibition project.
4. What was the impact of the Bombes?
By speeding up the process of breaking the day’s Enigma settings, Turing’s invention meant staff were able to decode quickly and pass on intelligence – often with enough time for it to be acted upon. Intelligence uncovered prior to the battle of El Alamein in 1942 contributed to victory in this Egyptian campaign,which proved to be a turning point of the war.
5. In which areas of the war did they have success?
The use of Bombes in intelligence gathering had a huge impact across many land, sea and air campaigns. The German battleship Bismarck was located with the assistance of Enigma decrypts and sunk by air and surface attack in 1941. Later, in 1944, Enigma decrypts provided details of German defensive preparations for, and reactions to the D-Day invasion.
6. What was the legacy of Turing’s creation?
The Bombes represented the first mass production of a specially designed cryptanalytical machine. They heralded the industrialisation of codebreaking and the intelligence they provided was crucial to Allied success in WW2. They were a significant part of the Bletchley Park operation, which was so successful that the Germans remained unaware the information sent on their “unbreakable” Engima machines had actually been cracked by the Allies.