In "Dead Wake: The Last Crossing of the Lusitania," Erik Larson describes how secure communications during World War I relied heavily on cipher keys that only certain individuals could decode. The complexity of deciphering these messages was significantly reduced by the possession of codebooks, which served as valuable resources for those involved in intelligence work.

To take advantage of these codebooks and enhance their capabilities in breaking messages, the British Admiralty created Room 40, a dedicated team focused on intercepting and interpreting enemy communications. This initiative played a crucial role in the naval intelligence efforts of the time, allowing for more effective strategic planning.