 Only the head of the German Naval Section, Frank Birch, and the mathematician Alan Turing believed otherwise.The British codebreakers needed to know the wiring of the special naval Enigma rotors, and the destruction of by in February 1940 provided this information.In early 1941, the Royal Navy made a concerted effort to assist the codebreakers, and on May 9 crew members of the destroyer boarded and recovered her cryptologic material, including bigram tables and current Enigma keys.