Eric Nave Captain Eric Nave ( 1899 – 1993 ) was a Navy Paymaster Commander and an Australian cryptographer , before and during World War II . He served in the Navy from 1917 to 1949 . As a midshipman in the 1920s , he was required to learn a foreign language and chose Japanese : " with French and German you got sixpence a day extra , ( but ) for Japanese you got five bob " ( ten times as much ) . He spent two years in Japan , and transferred to the Royal Navy Sigint section in 1925 , then the Government Code and Cipher School in London in 1927 . In 1930 he was sent to the Far East Combined Bureau , in Hong Kong and later in Singapore . He was invalided sick to Melbourne in 1940 where he set up a small RAN cryptographic unit in Victoria Barracks . The unit had a core of naval personnel , with an appreciable number of university academics and graduates specialising in classics , linguistics and mathematics , e . g . Athanasius Treweek and Arthur Dale Trendall . The unit outgrew Victoria Barracks , and moved to the Monterey building in February 1942 . But Monterey also housed FRUMEL , run by ( USN ) Lieut Rudi Fabian , ex - Station CAST in the Philippines . Nave was eventually forced out of Monterey by Fabian , who apparently regarded him as a " security risk " – because he wanted to cooperate with the Army ' s Central Bureau . According to his staff , Nave often kept keys to new codes passed on by the Americans and British to himself , which might have been acceptable as a training exercise in peacetime , but not in time of war . Treweek said : " We always looked forward to his day off . We ’ d get the keys to his safe and find all this material in there . " Nave also had difficulties with his superior , Commander Long , the Director of Naval Intelligence , whom he considered a man of no great ability . Nave eventually joined the Central Bureau at Brisbane . Joe Richard said that " [ i ] f Fabian did not want Nave , the US Army codebreakers were very happy to have him . . . Fabian ' s dislike of Eric Nave was very fortunate for us . Nave became an indispensable person " in " reading air - to - ground messages containing the weather " which " gave away the intended target for the day . " Nave and his department were in large part responsible for MacArthur being able to predict the Japanese military moves such as Milne Bay . The Australian codebreakers were responsible for warning the US Navy on 2 December 1941 that by the end of that week end USA would be at war with Japan . The response was that there were no hostile acts west of the date line . They were later warned that following Doolittle ' bombing raid the emphasis was changed from New Guinea to Midway Islands where the Japanese thought the bombing raid had come from . Later these code breakers warned MacArthur that Milne Bay was to be invaded ( then part of Australian Protectorate ) in one month ' s time in late August 1942 . This enabled a hurried reinforcement of Milne Bay . The Battle of Milne Bay was decisively won , mainly by Australian soldiers and US engineers ; it was the first time the Japanese had been defeated on land by the allies . Much of his 1991 book co - authored with James Rusbridger reflects Rusbridger ’ s views rather than his own , particularly the claim that Churchill concealed warnings about Pearl Harbor from Roosevelt in order to get America in the war . In a 1991 interview on Japanese television Nave " repudiated a large slice of what Rusbridger had written , calling it speculation . "