Signal intelligence is the most secret, and most misunderstood, weapon in the modern espionage arsenal. As a reliable source of information, it is unequalled, which is why Government Communications Headquarters, almost universally known as GCHQ, is several times larger than the two smaller, but more familiar, organisations, MI5 and MI6. Because of its extreme sensitivity, and the ease with which its methods can be compromised, GCHQ's activities remain cloaked in secrecy. In GCHQ: The Secret Wireless War, the renowned expert Nigel West traces GCHQ's origins back to the early days of wireless and gives a detailed account of its development since that time. From the moment that Marconi succeeded in transmitting a radio signal across the Channel, Britain has been engaged in a secret wireless war, first against the Kaiser, then Hitler and the Soviet Union. Following painstaking research, Nigel West is able to describe all GCHQ's disciplines, including direction-finding, interception and traffic analysis, and code-breaking. Also explained is the work of several lesser known units such as the wartime Special Wireless Groups and the top-secret Radio Security Service. Laced with some truly remarkable anecdotes, this edition of this important book will intrigue historians, intelligence professionals and general readers alike.