In 1974, Frederick Winterbotham's The Ultra Secret[1] inaugurated (for English-speaking readers) a major part of World War II historiography. Since then, dozens of books have assessed signals intelligence (SIGINT) during the war. I will review here three recent works that have found new ways to look at codebreaking from both sides of the battlefield.

Anglophone experts on the breaking of ENIGMA have long acknowledged the crucial contribution of Polish cryptologists at the beginning of the war. When, in 1926, the German navy sent its first Enigma machine messages, they were quickly intercepted by the Biuro Szyfrów—"Cipher Bureau"—which, however, could not decode them. The Poles owned a commercial version of Enigma, as did the British and French, but the German military had modified their version, adding a plugboard and rewiring the rotors. The messages it produced could not be read by the code-breakers of any country. The Poles, who had far more reason than any other nation to fear their neighbor to the west, tried a new tack: They hired three young mathematicians—Marian Adam Rejewski, Henryk Zygalski, and Jerzy Różycki—to see what they could do. By 1932, they had succeeded in determining how the German Enigma worked—an achievement that later astounded their French and British counterparts.

The entire story of the Polish contribution to solving Enigma and the fates of the men involved has not been told in English until now. In X, Y & Z: The Real Story of How Enigma Was Broken, Dermot Turing, a British lawyer (and Alan Turing's nephew), tells the Polish side of the Enigma story, tracing the lives of the cryptologists, mathematicians, and radio experts involved from 1926 to their eventual deaths. The crucial events of the late 1930s have been covered in previous books, but Turing clarifies how far the Poles were ahead of their French and British colleagues. He provides a dramatic account of the meeting of cryptologists in Poland on 27 July 1939, where the Poles demonstrated their understanding of the German military Enigma and revealed their invention of the bomba, the first electromechanical device for solving the machine's settings. "The Polish revelations had shortened the British attack on Enigma by at least a year" (124).

Only a few weeks after this meeting, of course, Poland was invaded from the west by the Wehrmacht and from the east by the Soviet Union. The Polish cryptologists fled as fast as they could southward to Romania and thence to France. The heart of X,Y & Z is the narration of their three years in France and Algeria as pawns in a complex game of double- and triple-cross. At first, the Poles worked for the intelligence agencies of the French Republic. When France fell and Vichy took over the administration of southern France, where the Poles were operating, they and their anti-German, anti-Vichy French sponsors continued to decipher German messages and collaborate with the British via radio. When the Germans occupied southern France in November 1942, some of the Poles were arrested and spent the rest of the war in captivity. Though a few made their way to England, none ever again did important work on German codes.

Though Turing does not emphasize it, there was a striking difference in the postwar fates of the World War II cryptanalysts. In Britain and the United States, they mostly went back to civilian life and died in their beds.[3] Ralph Bennett ended his career as president of Magdalene College, Cambridge.[4] Nearly all the "code girls" of Arlington Hall got married, as did the thousands of women who worked at BP.[5] The surviving top German officials were interviewed by TICOM. One of the Poles died on a ship that sank between Algeria and France; two others died in Sachsenhausen concentration camp—one during an Allied bombing attack. Marian Rejewski was the only analyst who returned to Poland, where he had to endure endless interrogations and persecution for his association with the prewar Polish army.

Dermot Turing has written a great book filling out our picture of Second World War code-breaking. His prose crackles with energy and an appealing sense of humor, enhanced by dozens of photographs, many of which will be new even to devoted students of his subject. An invaluable appendix explains how the Poles used math and machines to crack Enigma.