Alan Turing Timeline

After returning from Princeton, Turing attended Government Code and Cypher School (GC&CS) courses and worked part-time with its codebreakers. On September 4, 1939, the day after Britain declared war, he reported to Bletchley Park full-time.

Image source: GCHQ

Building on Polish breakthroughs, Turing designed an electromechanical device—the Bombe—that could rapidly determine daily Enigma key settings. The first Bombe, named 'Victory', began operating in March 1940, dramatically accelerating Allied decryption of German messages.

Image source: Bombe

Turing joined Britain's top-secret codebreaking centre at Bletchley Park, where roughly 10,000 people would eventually work on intercepting and decrypting Axis communications. He became a central figure in the effort against German naval ciphers.

Image source: Bletchley Park

Turing devised sophisticated techniques, including the Banburismus method, to attack the German Navy's more complex Enigma cipher used for U-boat communications. This work was vital to winning the Battle of the Atlantic and keeping Britain supplied.

Image source: Cryptanalysis of the Enigma

As head of Hut 8, Turing led the section responsible for naval Enigma decryption. The intelligence produced, codenamed Ultra, helped convoys evade U-boat wolfpacks and was decisive in the Battle of the Atlantic.

Image source: Hut 8

Frustrated by bureaucratic delays in staffing and funding, Turing and three other Hut 8 leaders wrote directly to Prime Minister Winston Churchill. Churchill responded immediately, ordering that requests be met 'with extreme priority'.

Turing developed the technique known as 'Turingery' for attacking the Lorenz cipher used in German high-command communications, contributing to the Colossus computer project led by Max Newman and Tommy Flowers at Bletchley Park.

Image source: Lorenz cipher

Turing travelled to America as Britain's technical liaison, visiting Bell Labs in New York to share cryptographic knowledge and inspect speech-encryption technology. There he encountered ideas about electronic digital systems that informed his later computing designs.

Image source: Bell Labs

For his crucial contributions to codebreaking, Turing received appointment as an Officer of the Order of the British Empire (OBE) in the New Year Honours, recognized publicly only as service to the Foreign Office due to wartime secrecy.

Image source: Order of the British Empire

At age 38, Turing was elected a Fellow of the Royal Society, one of Britain's highest scientific honours, recognizing both his wartime achievements and his foundational contributions to mathematics and computing.

Image source: Royal Society

Rather than face prison, Turing accepted probation conditioned on undergoing oestrogen injections designed to reduce libido. The treatment caused severe physical and psychological effects, and his security clearance was revoked, ending his consultancy for GCHQ.

Following a burglary at his home, Turing acknowledged a relationship with a man to police and was prosecuted under Victorian anti-homosexuality laws. He was convicted of gross indecency and given a choice between imprisonment and chemical castration.

Turing was found dead at his home in Wilmslow, Cheshire, having died of cyanide poisoning. An inquest ruled his death suicide, noting a half-eaten apple beside his body. He was 41 years old, and his death shocked colleagues who knew little of his persecution.

Image source: Alan Turing

Over the decades after his death, historians and scientists increasingly recognized Turing's pivotal wartime role and scientific genius. Former Bletchley colleague Peter Hilton famously estimated that Turing's work shortened the war in Europe by several years.

Image source: Legacy of Alan Turing

The ACM established the A.M. Turing Award, often described as the Nobel Prize of computing, awarded annually for major lasting contributions to computer science, ensuring Turing's name remains central to the field he founded.

Image source: Turing Award

Frederick Winterbotham's book 'The Ultra Secret' disclosed the scale of Bletchley Park's codebreaking triumphs, allowing the public to finally grasp the enormous strategic importance of Turing and his colleagues' secret wartime work.

Image source: Ultra (cryptography)

Commemorations of Turing grew through the late 1990s, culminating in memorials such as the bronze statue at Bletchley Park and the Alan Turing Memorial statue in Manchester's Sackville Park depicting him holding an apple, honouring the man once shunned by the state.

Image source: Alan Turing Memorial

Following a public petition, Prime Minister Gordon Brown issued an official apology for the 'appalling' way Turing was treated, acknowledging the injustice of his conviction and the debt owed to his wartime contributions.

Image source: Gordon Brown

Queen Elizabeth II signed a rare posthumous royal pardon formally forgiving Turing's 1952 conviction, four years after the government apology. The pardon followed campaigns by scientists, politicians, and activists seeking justice for Turing.

Image source: Alan Turing

The Policing and Crime Act 2017, dubbed 'Turing's Law', granted posthumous pardons to tens of thousands of men convicted of same-sex offences under historical laws that criminalized homosexuality in England and Wales, extending Turing's pardon to thousands like him.

Image source: Policing and Crime Act 2017