 Australia was one of the first nations to commit units to the fighting , playing a small but sometimes significant part in the United Nations Command , which was initially led by General Douglas MacArthur . Forces deployed in Japan as part of the British Commonwealth Occupation Force ( BCOF ) formed the basis of the Australian response , with P @-@ 51 Mustang fighter @-@ bombers from No. 77 Squadron RAAF flying their first missions on 2 July , while the frigate HMAS Shoalhaven and the destroyer HMAS Bataan were also committed to naval operations . During this time the 3rd Battalion , Royal Australian Regiment ( 3 RAR ) , which had been preparing to return to Australia prior to the outbreak of the war , remained in Japan , however on 26 July the Australian government announced that it would also commit the under @-@ strength and poorly equipped infantry battalion to the fighting , following a period of preparation . Training and re @-@ equipment began immediately , while hundreds of reinforcements were hastily recruited in Australia as part of K Force ; they soon began arriving to fill out the battalion . The battalion 's commanding officer , Lieutenant Colonel Floyd Walsh , was replaced by Lieutenant Colonel Charles Green . An officer with extensive operational experience fighting the Japanese in New Guinea during the Second World War , Green took over from Walsh due to the latter 's perceived inexperience . 
