Political map of Australia, New Zealand & the Southwest Pacific 08 May 1942 (Battle of the Coral Sea): After conquering the East Indies (Dutch East Indies campaign), Japan shifted its focus to cutting Australia's supply line to America. In May, it attempted to send an invasion fleet to occupy Port Moresby (Operation Mo), but ran into an American carrier force in the Coral Sea. The ensuing battle (Battle of the Coral Sea) was dominated by aircraft carriers, with neither side's ships sighting each other.