Behind the Enigma, a history of British signals intelligence (sigint) from its origins in World War I to 2020, is not for the faint of heart. Historian John Ferris (Univ. of Calgary) has achieved several things in this massive tome, but it will surprise many readers. Though the book is a lengthy authorized history, written with access to the Government Communications Headquarters (GCHQ) and its archives and staff, it does not resemble F.H. Hinsley's four-volume study of the subject.[1] Nor is it a hagiography of British codebreakers in Room 40 (World War I), Bletchley Park (World War II), and the Cold War. Instead, Ferris offers sharp judgments of the successes and failures of British communications intelligence and its personnel.

Ferris begins with a swift introduction to the offensive and defensive aspects of communications intelligence in Britain from ca. 1690 to 1914; from opening other people's mail to intercepting their telegrams, to protectively encoding the correspondence of British diplomats. All this changed when armies and navies adopted wireless communications and the Great War broke out. Suddenly, the airwaves were full of messages, and signals intelligence was born.

The author describes World War I sigint in a terse 37-page chapter on, among other things, Room 40 (the Admiralty's radio intelligence agency) and clashes between the Grand Fleet and the Kaiser's High Seas Fleet, including the Battle of Jutland. But the war on land is not omitted. Ferris judges that British and German sigint capabilities on the Western Front were equal in quality. On the sea, however, sigint enabled the Royal Navy to thwart the Germans at low cost. In the larger picture, "These British (and Allied) triumphs were largely cancelled out by those of Austro-Hungarian and German Sigint, which helped smaller forces to demolish a larger Russian army" (64).

After briefly describing various interwar activities, Ferris reaches what many readers will be looking for: World War II codebreaking, Bletchley Park, Enigma, etc. But the two long chapters he devotes to the war—"Bletchley" and "Ultra and the Second World War, 1939–1945"—are not a narrative of the intelligence war, highlighting the thrilling grabs of rotors and papers from U-boats and weather ships, or the seesaw cryptology war during the Battle of the Atlantic. The only naval battle described in detail is the Battle of Cape Matapan (27–29 Mar. 1941), a major Royal Navy victory over the Italians, chosen to show how even bits of sigint, combined with good leaders and superior technology, changed the outcome of first one battle and then the naval war in the Mediterranean. Ferris offers more analysis and judgment than straight narrative:

When the war ended, GCHQ found itself in a new and awkward position. Thousands of codebreakers had contributed to shortening, if not winning, the war, yet they were all sworn to eternal secrecy. At the same time, a much poorer Great Britain needed to cut every government agency's budget as the nation continued to impose food rationing on its people. Ferris carefully details how GCHQ managed, through the Cold War and beyond, to acquire the funds and people it needed to continue its work. The postwar landscape differed dramatically from the world of 1939. The British Empire was dissolving, the Soviet Union and the United States dominated the globe, and GCHQ had to help governments and prime ministers navigate unfamiliar waters. A sensitive new issue was the UKUSA agreement, which governed collaboration between GCHQ and the agencies that became the US National Security Agency (NSA).

Ferris expertly explains the elaborate dance of the two nations' codebreakers. In the beginning, the United Kingdom enjoyed advantages in staff and number of listening stations around the globe (thanks to the empire), and longer and broader experience. Eventually, however, this changed: the rich Americans, with their huge Cold War defense budgets, hired far more people than the United Kingdom could afford, while British stations in India and Africa, for example, were being abandoned. The advent of computers and then satellites greatly lengthened the American' lead, to the point that NSA had to subsidize its British colleagues. Ferris notes that the UKUSA agreement was sometimes tested by situations—the 1956 Anglo-French attack on Egypt, for example, where British and American policy goals collided.

The book's purview extends beyond codes and crises. Since it is the history of an agency, several chapters concern institutional aspects of GCHQ in the Cold War and post-Cold War eras up to 2020. British readers, in particular, will be interested in Ferris's discussion of the decision to move the agency to Cheltenham in 1952. This small city, best known as a Regency spa, was far from London and other government offices. Precisely. It offered privacy and cheap land, and GCHQ soon became the dominant employer of both men and women when they finished school. Ferris provides portraits of several agency directors, with special attention to Sir Eric Jones, who headed GCHQ from 1952 to 1960 and was a Bletchley Park veteran; otherwise he was an odd choice for the position. He was, Ferris notes more than once, a businessman without an Oxbridge education—he never attended university at all! But he proved to be an excellent manager. The author also discusses the long, difficult struggle of women to rise from clerical jobs to management positions at the agency.

Behind the Enigma does not give a chronological accounting of GCHQ's actions during the Cold War. Ferris observes that high-level Soviet codes were never broken, without going into detail. He does, however, highlight three postwar challenges. One of these was Palestine. Britain controlled this region, but the Zionists, the Palestinian Arabs, and the surrounding countries wanted control, for widely different reasons. Faced with the militant Jews already living in what would become Israel and hundreds of thousands of refugees fleeing a Europe that had sought to kill them, the British tried to monitor their communications. But many of their messages were in Hebrew, and the only Hebrew-speakers the British might recruit were Jews. Ferris ends this section with a typically acerbic comment:

The book has a long section on Britain's "Konfrontasi" with Indonesia in the 1950s and 60s. Once again, as the empire shrank, British intelligence agencies tried to help diplomats and soldiers limit losses and shore up allies. One very late example came in 1982 when, in a move that shocked Prime Minister Margaret Thatcher's government, Argentina invaded the Falkland Islands. By then, GCHQ was no longer closely monitoring the world, and, of course, Buenos Aires' communications were not a priority. When Thatcher decided to respond with force, the agency scrambled to find Spanish-speakers and penetrate Argentina's codes. Fortunately for GCHQ, the Argentine military was at least as poorly prepared for the war as the British.

The section on the Falklands War illustrates a problem many readers will have with Behind the Enigma. Though Ferris mentions many prominent events of the war—the sinking of General Belgrano, the loss of HMS Sheffield, the decision to land at San Carlos Water—here and elsewhere he gives no overview or chronologic sense of the conflict.[2] Specialists in twentieth- and twenty-first-century military history will learn a great deal about the influence of comint and sigint on the wars John Ferris discusses. Others may be lost.