In the immediate post @-@ war period Australia contributed significant forces to the Allied occupation of Japan as part of the British Commonwealth Occupation Force ( BCOF ) , which included forces from Australia , Britain , India and New Zealand . At its height in 1946 the Australian component consisted of an infantry brigade , four warships and three fighter squadrons , totalling 13 @,@ 500 personnel . The Australian Army component initially consisted of the 34th Brigade which arrived in Japan in February 1946 and was based in Hiroshima Prefecture . The three infantry battalions raised for occupation duties were designated the 1st , 2nd and 3rd battalions of the Royal Australian Regiment in 1949 , and the 34th Brigade became the 1st Brigade when it returned to Australia in December 1948 , forming the basis of the post @-@ war Regular Army . From that time the Australian Army contribution to the occupation of Japan was reduced to a single under @-@ strength battalion . Australian forces remained until September 1951 when the BCOF ceased operations , although by the time the majority of units had been committed to the fighting on the Korean peninsular following the outbreak of the Korean War in 1950 . The RAAF component consisted of Nos. 76 , 77 and 82 Squadrons as part of No. 81 Wing RAAF flying P @-@ 51 Mustangs , initially based at Bofu from March 1946 , before transferring to Iwakuni in 1948 . However , by 1950 only No. 77 Squadron remained in Japan . A total of ten RAN warships served in Japan during this period , including HMA Ships Australia , Hobart , Shropshire , Arunta , Bataan , Culgoa , Murchison , Shoalhaven , Quadrant and Quiberon , while HMAS Ships Manoora , Westralia and Kanimbla also provided support .