A Blue Plaque marking Turing's home at Wilmslow, Cheshire, UK

Alan Turing was not only one of brightest mathematicians of the 900s and a genuine pioneer in the field of computer science, but also a hero of World War II for his decisive contribution to crack the Enigma code.
Enigma was an electro-mechanical machine used in several versions by the Wehrmacht and Kriegsmarine, the german military navy, to cipher and decipher their messages.

Since the enormous importance to succeed in cracking the code produced by Enigma the english Government Communications Headquarters founded in 1939 at Bletchley Park a centre for uncoding war messages, particularly for the cryptanalysis of the Enigma in Hut 8, which was led by Turing for a certain time.

Turing joined the Bletchley Park centre at the beginning of the war, working mainly on the naval version of, developing a number of techniques of analysis and deciphering, using a refined version of a computing machine called the "Bombe" already used in the past with success by the Polish Cipher Bureau which, at the outbreak of war, passed the results to english. The techniques which developed are named Banburismus for the Enigma machine and Turingery (or Turing's Method) for the Lorenz machine. Since 1941 the Enigma decoding projectil was known as Ultra and shared with the Allies. Turing contributed decisively to break the Enigma machine code of the navy version, resulting in a turning point for the Atlantic naval war.

In 1945 Turing was awarded the OBE for his wartime services, though his work remained secret for many years.

In 1952 Turing reported to the police for a break into his house by an his friend's accomplice. During the investigation he admitted to be homosexual and acknowledged a sexual relationship with that friend, saying "What's wrong?".
Homosexual acts were illegal at that time in the respectable, repressive and homophobic U.K. and Turing was charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885, the same crime for which Oscar Wilde had been convicted more then fifty years earlier.
Turing was given a choice between imprisonment or probation conditional on his agreement to undergo chemical castration, which he accepted.

Turing was a playful figure, he invented a way to play chess called "turn around the house": when a player moved he ran around the house, if the other player had still to move, he could make a further move.

Even in the implementation of his suicide Turing did not miss to get an humor's touch: as in the Snow White fairy tale, one of his favourite, on June 8, 1954 he injected cyanide poisoning into an apple and ate it.

The story of the treatment to which Alan Turing was subjected is one of the most infamous in British history.

Only on September 10, 2009, acknowledging an internet e-petition started by John Graham-Cumming, the former prime minister Gordon Brown released on the official site a public and personal statement, apologising and describing Turing's homophobic treatment as "appaling":

Text of Gordon Brown's statement on Alan Turing

Prime Minister: 2009 has been a year of deep reflection – a chance for Britain, as a nation, to commemorate the profound debts we owe to those who came before. ... So I am both pleased and proud that, thanks to a coalition of computer scientists, historians and LGBT activists, we have this year a chance to mark and celebrate another contribution to Britain’s fight against the darkness of dictatorship; that of code-breaker Alan Turing.

Turing was a quite brilliant mathematician, most famous for his work on breaking the German Enigma codes. It is no exaggeration to say that, without his outstanding contribution, the history of World War Two could well have been very different. He truly was one of those individuals we can point to whose unique contribution helped to turn the tide of war. The debt of gratitude he is owed makes it all the more horrifying, therefore, that he was treated so inhumanely. In 1952, he was convicted of ‘gross indecency’ – in effect, tried for being gay. His sentence – and he was faced with the miserable choice of this or prison - was chemical castration by a series of injections of female hormones. He took his own life just two years later.

Thousands of people have come together to demand justice for Alan Turing and recognition of the appalling way he was treated. While Turing was dealt with under the law of the time and we can't put the clock back, his treatment was of course utterly unfair and I am pleased to have the chance to say how deeply sorry I and we all are for what happened to him. Alan and the many thousands of other gay men who were convicted as he was convicted under homophobic laws were treated terribly. Over the years millions more lived in fear of conviction.

I am proud that those days are gone and that in the last 12 years this government has done so much to make life fairer and more equal for our LGBT community. This recognition of Alan’s status as one of Britain’s most famous victims of homophobia is another step towards equality and long overdue.

But even more than that, Alan deserves recognition for his contribution to humankind. For those of us born after 1945, into a Europe which is united, democratic and at peace, it is hard to imagine that our continent was once the theatre of mankind’s darkest hour. It is difficult to believe that in living memory, people could become so consumed by hate – by anti-Semitism, by homophobia, by xenophobia and other murderous prejudices – that the gas chambers and crematoria became a piece of the European landscape as surely as the galleries and universities and concert halls which had marked out the European civilisation for hundreds of years. It is thanks to men and women who were totally committed to fighting fascism, people like Alan Turing, that the horrors of the Holocaust and of total war are part of Europe’s history and not Europe’s present.

So on behalf of the British Government, and all those who live freely thanks to Alan’s work I am very proud to say: we’re sorry, you deserved so much better.

Alan Turing memorial statue in Sackville Park, Manchester

Since 1966 by ACM - Association for Computing Machinery a Turing award has been given annualy to honor his memory. It is widely considered as the computing world's highest honour in the fields of computer science, intelligent systems and artificial intelligence.