155 Western Union, which has the telegraph monopoly in America, to provide the Black Chamber with all the telegrams coming into the United States. “Its far-seeking eyes penetrate the secret conference chambers at Washington, Tokyo, London, Paris, Geneva, Rome,” Yardley wrote about the Black Chamber. “Its sensitive ears catch the faintest whispering in the foreign capitals of the world.” But in 1929, at the instructions of President Herbert Hoover, Secretary of State Henry Stimson closed the Black Chamber saying famously “Gentlemen should not read each other's mail.” The moratorium did not last long. With war looming in Asia and Europe, President Franklin D. Roosevelt reactivated the operation as the Signals Security Agency. It proved its value in breaking the Japanese machine-generated cipher “purple.” In June 1942, using deciphered Japanese messages to pinpoint the location of the Japanese fleet at Midway; America’s won a decisive naval victory in the Pacific. Germany’s Enigma encoding machines, with three encoding wheels, proved more of a challenge. Initially British cryptanalysts led by the brilliant mathematician Alan Turing succeeded in building a rudimentary computer to decipher German messages to its submarines and bombers, but, in 1942, Germany added a fourth set of encoding wheels, escalation what essentially was a battle of machine intelligence. The US Navy then contracted with the National Cash Register Company to build a computing machine capable of breaking the improved Enigma, and, in May 1943, it succeeded. By the time the war ended in 1945, the US had over one hundred giant decryption machines in operation. This unrivalled capability to read the communications of foreign nations, which remained one of America’s most closely guarded secrets, was transferred to the Army Security Agency based at Fort Meade, Maryland. Then, on October 24, 1952, President Harry S. Truman, greatly expanded its purview and changed its name to the National Security Agency.