UltrA

UltrA was an Allied intelligence system that, in tapping the very highest-level communications among the German armed forces, as well as (after 1941) those of the Japanese armed forces, contributed to the Allied victory in World War II.

In 1938 a Polish mechanic employed in a German factory producing secret signaling machines named EnigmA (which worked on the basis of a set of preset revolving drums) took notes of the components before being repatriated and, with the help of the British and French secret services, constructed a wooden mockup of the machine. A British cryptographer later smuggled a complete new EnigmA machine to EnglanD?. There, British mathematicians and cryptographers conquered the problems of EnigmA variations and found means of cracking the CipheR's. Early in 1939 Britain's secret service set up the UltrA project at BletchleyPark?, 50 miles (80 km) north of LondoN?, for the purpose of intercepting the Germans' EnigmA signals and controlling the distribution of the resultant secret information. Strict rules were established to restrict the number of people who knew about the existence of the UltrA information and to ensure that no actions would alert the Axis powers that the Allies possessed knowledge of their plans.

The incoming signals from the German war machine (more than 2,000 daily at the war's height) were of the highest level, even from AdolfHitler himself. Such information enabled the Allies to build up an accurate picture of enemy plans and orders of battle, forming the basis of war plans both strategic and tactical. UltrA intercepts of signals helped the Royal Air Force to win the Battle of Britain. Signals between AdolfHitler and General Günther von Kluge led to the destruction of a large part of the German forces in NormandY? in 1944 after the Allied landing. In the Pacific the Germans had supplied their Japanese ally with an EnigmA machine as early as 1937; the modified Japanese version, called "Purple" by the Americans, was duplicated by the U.S. Signal Intelligence Service well before PearlHarbor?. Resultant revelations of Japanese plans led to U.S. naval victories in the battles of the Coral Sea and Midway, crushing the offensive power of the Japanese fleet, and enabled American flyers to find and shoot down the plane carrying Admiral Yamamoto Isoroku, the Japanese commander in the Pacific.

For 29 years after the war the existence of UltrA remained an official British secret. The ban was not lifted until 1974, the year that a key participant in the UltrA project, Frederick William Winterbotham, published The UltrA Secret.