The Other Ultra - Ronald Lewin [BluA].epub

Summary:
The story of the contribution made by Ultra, the intelligence derived from deciphering of the Germans’ Enigma-coded signals, is now well-known.

But what of The Other Ultra?

Based on contemporary secret documents only recently released, tells for the first time the story of the immense contribution made by signal intelligence to the war against Japan.

This intelligence was of two kinds: the intelligence known as Magic, gathered from the breaking of the Japanese diplomatic signals enciphered on the machine called Purple; and the intelligence derived from the breaking of the Japanese naval and military codes, known to the Americans comprehensively as Ultra. The value of the latter in particular was dramatically summarized in a letter from General Marshal to Governor Dewey while the war was at its height: ‘Operations in the Pacific are largely guided by the information we obtain of Japanese deployments.’

The story of Magic and of this other Ultra begins and ends with major controversy, with the question of how much the American authorities were in a position to know about Japan’s precise intentions towards Pearl Harbor in the autumn of 1941, and the question, which will probably never be resolved, as to whether the use of the A-bomb was justified by the appalling losses that would otherwise have been sustained if the islands of Japan had been invaded.

But between these two points Magic and Ultra intervene, often decisively, at almost every point in the struggle in the Pacific: in the great naval battles in the Coral Sea and Midway, where Ultra enabled Admiral Nimitz to place his carriers in the right place at the right time; in the long and bitter struggle on Guadalcanal and in the Solomons; in the death of Admiral Yamamoto; in the direction of American submarine forces and in the destruction of Japanese merchant shipping.

Only General MacArthur, with his ambiguous attitude towards this intelligence, stands out as an American commander who probably did not derive as much benefit from it as he might have done.

Together with traffic analysis and the courageous work of the coastwatchers, many of them Australian, the contribution of Ultra to the ultimate victory over Japan was incalculable. Ronald Lewin’s history adds to the story of the war in the Pacific, and is an essential book on the conflict.