The German attack on merchant shipping in the Second World War, known as the Battle of the Atlantic, was countered partly by code-breaking intelligence known as

This book contains the U-boats situations and trends written by the staff of the Admiralty’s Operational Intelligence Centre during the Second World War. Base

These documents relate on a weekly, and in some cases a daily, basis exactly what the Allies knew concerning the activities of the U-boats during the Battle of

From LORENZ to ENIGMA, Room 40 to Bletchley, SIGINT reveals the story of the secret signals of both world wars