Japanese army (IJA) and diplomatic codes were studied at Arlington Hall (US), Bletchley Park (UK), Central Bureau or CBB (Australian, US; in Melbourne, then Brisbane), the FECB (British Far East Combined Bureau) at Hong Kong, Singapore, Kilindi then Colombo and the British Wireless Experimental Centre in Delhi.
Richard was assisted at Central Bureau by Major Harry Clark and by the head, Abraham "Abe" Sinkov, and broke 2468 on 6 April 1943, for which he was awarded the Legion of Merit.
First broken by the Bletchley Park air section, it provided vital tactical information, so work on it was carried out in India at the Wireless Experimental Centre in Delhi.
Traffic from the army operational flying units based around Meiktila in Burma was particularly valuable, aided by a book and some additive sheets from a Japanese aircraft shot down over India.
[9][10] In January 1944, Mainline Japanese Army codes were broken with help from a buried trunk found during the Battle of Sio in New Guinea by Australian troops of the 9th Division.
Tokyo was told the papers had been burnt, but the Japanese lieutenant did not want to reveal his position by burning them, so they were buried in a metal strongbox near a stream.
The Central Bureau spent a day drying the damp pages, and the flood of decoded messages that ensued meant that MacArthur had to ask the U.S. Navy for assistance.
[12][13] Major Sinkov and his team of Americans and Australians from Central Bureau photographed every dried page and sent these photocopies immediately to Arlington Hall, the headquarters of the U.S. Army Signal Intelligence Service, for decryption.
But decrypted Purple traffic was valuable militarily, particularly reports from Nazi Germany by Japanese diplomats and military and naval attachés.
[18] The fourteen-part message breaking off negotiations with the United States in December 1941 on the eve of Pearl Harbor was in Purple; and was translated by the Americans in advance of the Japanese embassy staff who were preparing it for delivery.
In July and August 1942 Oshima toured the Russian front, and in 1944 he saw the Atlantic Wall fortifications against the expected Allied invasion along the coasts of France and Belgium.