<P> General of the Army Douglas MacArthur was appointed Supreme Allied Commander , South West Pacific Area ( SWPA ) on 18 June 1942 . However , he preferred to use the title Commander - in - Chief . During the Allied occupation of Japan following the war , MacArthur held the title of Supreme Commander for the Allied Powers ( SCAP ) . </P>
full name of the allied commander of the pacific war
General of the Army Douglas MacArthur was appointed Supreme Allied Commander , South West Pacific Area ( SWPA )