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The secret history of signals intelligence


Signals intelligence, or SIGINT, is the interception and evaluation of coded enemy messages. From Enigma to Ultra, Purple to Lorenz, Room 40 to Bletchley, SIGINT has been instrumental in both victory and defeat during the First and Second World War.

The war in Europe was shaped and won for the Allies in the Pacific. In 1941 the Japanese Government was planning to attack America and the British in the Pacific but faced a problem. Russian troops were massed along the boarder with Manchuria where the Imperial Japanese Army was fighting the Chinese. Tokyo felt itself vulnerable to attack at any moment. The Russians, on the other hand were fighting a life and death battle against the German invaders whose army had advanced to the suburbs of Moscow.

To release army formations on both sides of the boarder the Russians and Japanese governments signed a Non Agression Pact which had global implications. The Russian reinforcements, who were mainly Mongolian and accustomed to Siberian weather, made a surprise attack on the German panzers in the depths of the Russia’s winter. The Red Army hurled back the Germans from the suburbs of Moscow and began its long campaign that finally ended in Berlin and victory for the Allies. Meanwhile the Japanese had gained the confidence with the protection of the treaty and the extra troops available to them declared unprovoked war and attacked Pearl Harbor.

America lacked the understanding of codes in the run up to war, so could not comprehend the importance of the Pact but they proved fast learners. The cracking of the Japanese Purple codes by America and her Allies runs through the campaigns of the Pacific like a golden thread as does the deciphering of the German Enigma in Europe. Purple guided the American commanders to victory in the classic sea battles of Coral Sea, Midway and many other actions in the Pacific. The domination of signals intelligence by American and Allied forces in both the European and Pacific theatres of war is a true tale of high adventure. 

Secret documents captured by the American army and not declassified by the US State Department until recently form a basis of the book SIGINT: The Secret History of Signals Intelligence. They tell a true and unique story of how coding and deciphering signals messages enabled American commanders to listen to the authentic voice of the enemy with the resulting high value intelligence. Veteran German cryptographers in Berlin gave the author an insight into how the signals intelligence war operated in Europe with its successes and failures. Confidential papers of the American and Allies intelligence teams added value as an incredible picture emerged of Hitler’s intelligence networks and the way it operated. The book evaluates the way that German signals intelligence measured up against the Allied networks.

There is a twist in the tale, as the war ended the American army and the newly formed CIA did a deal worth millions of dollars with one of their prisoners of war. They rescued Abwehr military intelligence records of espionage networks on the Russian front. These provided the basis for a readymade intelligence agency that was to be used to good effect against the Russians in the early stages of the Cold War. The Gehlen Organisation, as it was known, became a principal German agency and has become a part of the global intelligence community.

By Peter Matthews

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