We read a lot about successful Allied espionage operations in WW2, but rarely about Axis operations. Operation Cicero was one such operation, which took place in the Turkish capital Ankara in 1943.
Cicero was the code name for the British Ambassador's valet, who photographed top-secret documents that the Ambassador kept in his personal safe and document boxes. He sold them to the Germans through his handler, L.C.Moyzisch, who was an attache at the German embassy. Moyzisch wrote his account of the affair in a 1950 book, which I recently found a copy of in a second-hand bookshop.
Cicero's motives appear to be largely financial. He was paid some £300,000 for around four hundred photographed documents. Some of these were very important, including partial notes of the Moscow, Tehran and Cairo conferences. He also handed over a document that mentioned Operation Overlord, although not what it meant. However, the Germans did discover that Turkish deception plan for Overlord from another document.
The Germans appear to have made limited use of this intelligence, partly because of turf wars in Berlin. Ribbentrop suspected that the documents were false, even after it was obvious they were genuine. He had a personal antipathy to the German ambassador in Turkey, Franz von Papen, who had been the German Chancellor.
This book is, of course, one person's account. Von Papen suggests in an annexe to the book that there is more to the story, although he confirms the main facts. Cicero was subsequently identified as Elyesa Bazna, and he wrote his own account in 1962. He was never caught by the British, leaving the embassy in April 1944 when the British recognised that the embassy was the source of the leaks. He lived in Turkey after the war and later moved to Munich. He died in Germany in 1970, aged 66.
They say treachery never pays, and in this case, they may be right. Most the money he was paid was in counterfeit Sterling and he spent a short time in a Turkish prison as a consequence. He tried unsuccessfully to get the West German government to reimburse him in the 1960's!
This is an interesting story that tells us a bit about Turkey in WW2 and the way German intelligence services operated.
A film based on this book was released in 1952. It was titled 5 Fingers and Bazna, renamed Ulysses Diello, was played by James Mason. I haven't watched it yet,(it's on YouTube) and it was nominated for two Academy Awards.