You'd never know by looking at the cluster of nondescript buildings that they were the scene of the single most important effort to defeat Nazi Germany. During World War Two, Bletchley Park in Milton Keynes, England, was home to thousands of code breakers listening in on and analyzing German military transmissions. The site was so secret that its existence wasn't revealed to the world until the 1970s.

It was here that the famous German Enigma and Lorenz code machines were broken, allowing the Allies to follow German troop, air, and naval movements. It's impossible to say just how much this helped the war effort, but one intelligence historian, Sir Henry Hinsley, estimated it shortened the war by up to four years.

The work on Enigma was actually started by the Polish Cipher Bureau, which broke the Enigma code five weeks before the war started. They shared the information with their British and French counterparts. Although Poland was soon overrun, many Poles fled to the UK to continue the fight. The Poles also sent over a cloned version of the Enigma machine, which proved invaluable.

Of course the Third Reich continued to improve and change the Enigma code, but this early head start helped the Allies keep listening. The Polish machine was later used as the basis for the "Bombe", a more sophisticated machine the British used to decipher Enigma transmissions. It's shown above in this photo courtesy Tom Yates.

More than 12,000 people worked at Bletchley Park at some time during the war, the majority of them women. Cryptographers were recruited from universities as well as more unusual sources such as chess clubs. Basically anyone who had a knack for puzzles was considered desirable. In one famous incident, the Daily Telegraph hosted a contest to see who could solve their crossword in under 12 minutes. The fastest winners were offered a job.

Despite its obvious historic importance, the site has been struggling with funding for a long time. Now it's had a change of fortune, with a £4.6 million injection courtesy the Heritage Lottery Fund and the listing of its Block C as a Grade II building, meaning it will be preserved for all time. Block C housed the massive library of punch cards used by Colossus, the world's first programmable digital electronic computer. Colossus was used to analyze the sophisticated German Lorenz code.

Today most of the original buildings are open to the public and tell the story of the secret fight against the Axis powers. The original buildings house a wonderland of old tech, as you can see in the gallery to this article. The site also houses the National Museum of Computing and the Radio Society of Great Britain. Bletchley Park is within walking distance of Milton Keynes station, making it an easy day trip from London.

Gallery: Bletchley Park

Filed under: History, Learning, Europe, United Kingdom