Once again the Japanese found themselves forced to flee into the rugged mountains in order to escape encirclement. As they sidestepped inland around Saidor, the retreating Japanese left a trail of abandoned equipment. On 15 January 1944, an Australian patrol pushing through Sio after the fleeing enemy discovered a half-buried trunk in a stream bed. It held the complete cipher library of the Imperial Japanese Army’s 20th Division. The find was immediately returned to Central Bureau, MacArthur’s Allied cryptanalytic agency in Brisbane, Australia. Central Bureau used the captured code books to solve the Japanese Army’s main cipher system. This intelligence windfall arrived exactly when MacArthur was most prepared to take advantage of it.
New Guinea 24 January 1943-31 December 1944