Secret Weapon: U.S. High-Frequency Direction Finding in the Battle of the Atlantic (review)

While the theme of this book is the contributions of the French engineer Henri Busignies to the development of HF/DF (high-frequency direction finding), or “Huff Duff,” as it was known, for the United States Navy, Secret Weapon is really a much wider ranging handbook on the electronic side of the Battle of the Atlantic, 1939–43. It is also filled with information that should be of primary interest to historians of technology because it shows all the impediments to the progress of modern technology.

Williams points out that the whole matter of locating U-boats by their transmissions was one in which the German Grand Admiral Karl Dönitz played into Allied hands by his insistence on controlling the war at sea by radio while refusing to concede that the Allies might break the German codes. Break them they did, of course. This in itself was not fatal, because Allied decryption became consistently reliable only from December 1942 onward, but the commander-in-chief of the U-boats insisted that his captains keep him informed. So even though they used a new “burst” transmission technology, they still revealed their positions because they had to surface to transmit. By 1942 the British had developed HF/DF sets and had trained operators to help escort commanders such as Capt. Donald MacIntyre of the Royal Navy dispatch his ships on a line of bearing to force a U-boat to submerge and, with luck, attack and sink her. The Allied antisubmarine campaign advanced significantly with the development of the first very-long-range aircraft, short-range TBS (talk between ships) radio, and antisubmarine warfare (ASW) escort-carrier task forces. The book’s weakness is that it does not handle the airside adequately in assessing the success of the Allied antisubmarine campaign, which went from near-disaster to victory in the crucial months between March and May 1943.

The United States Navy entered the war in December 1941 woefully behind technologically in spite of help from the British and was only just beginning to hit its stride in the Atlantic by mid-1943. This backwardness was in part due to the Anglophobe Chief of Naval Operations Ernest J. King’s reluctant recognition that the war in Europe, and therefore the war in the North Atlantic, had to be won first. There had been parallel developments of sonar and radar on both sides of the Atlantic, as there were for HF/DF. Their suspicions of the French had prevented the British from integrating Busignies’s cathode-ray display HF/DF into their own work on the FH-3 and then FH-4 sets fitted to British escorts. With the fall of France in June 1940, the ITT (International Telephone and Telegraph) French team was, with reluctant American help, smuggled out to the United States. There they were treated with isolationist suspicion, and ITT was even penalized for being a special international company. Thus it was some time before the valuable French connection was given full rein and before U.S. warships were equipped with effective direction-finding equipment. Even then, senior officers did not always understand what they had. Moreover, although the Americans could vastly outproduce the British and therefore supply enough equipment, the sets were not effective at sea because of a lack of trained operators.

Williams provides insights along with the history of one of the many revolutionary developments of the period 1934–45. The stories of radar, sonar, the airside, and now HF/DF have been told. Historians now need to focus on the mundane matter of training personnel to handle these revolutionary technologies of the wartime decade and educating commanders to understand the strengths and weaknesses of each new invention. We also need to look at how those who did not have these advantages, notably the Canadians (studied by Marc Milner in North...