Operation Ruthless - Background

Background

With the help of their Polish allies, British codebreakers at Bletchley Park had considerable success in decoding the Enigma-enciphered traffic of the German air force, army and intelligence and counter-espionage service (Abwehr), but had made little progress with German naval messages. The methods of communicating the choice and starting positions, of Enigma's rotors, the indicator, were much more complex for naval messages. In late summer 1940 Dilly Knox, the veteran World War I codebreaker, Frank Birch, head of Bletchley Park's German Naval Department, and the two leading codebreakers, Alan Turing and Peter Twinn knew that getting hold of the German Navy Enigma documentation was their best chance of making progress in breaking the code.

The Royal Navy's Operational Intelligence Centre (OIC) was a leading user of Ultra intelligence from Bletchley Park's decrypts. Lieutenant Commander Ian Fleming of the Admiralty's Naval Intelligence Division, who later wrote the James Bond novels, was the personal assistant to the Director of Naval Intelligence, Rear Admiral John Godfrey. Fleming liaised with the naval department at Bletchley Park, visiting about twice a month, and was well aware of this problem.