Birch's team initially concentrated on the minority of German naval messages using hand systems. These messages sometimes produced intelligence directly, but they also revealed how the communications network worked and could provide clues for attacking Enigma. Birch supported Turing's work on the naval problem and gave him a place in Hut 4 before Hut 8 became available. Cryptographic research depended on that accumulating knowledge of German naval communications. Expanding codebreaking-machine capacity also required an institutional campaign against objections over cost, skilled labour and electrical power.
Notable Point · 32:53-34:58
Naval Enigma required organization and machine capacity
Work on simpler German communications and investment in codebreaking machinery supported the attack on naval Enigma.