Costly in casualties and suffering, this campaign taught lessons that the Army had to learn if it was to cope with the Japanese under conditions of tropical warfare. By mid-1942 the Japanese forces were threatening to take the colonial capital of Port Moresby and therefore gain a base to launch their proposed invasion of Australia.
The allied forces needed to blunt the Japanese thrust toward Australia and thus protect the transpacific line of communications, as well as to secure a favorable position to take the offensive to the Japanese.
Yet this was easier planned than executed; the Australians had been battered through two years of combat with their enemies and although the Americans were bringing large numbers of reinforcements, they were living under intolerable conditions, plagued by disease, short of equipment, ill-prepared for jungle fighting, and pitted against a skilled and resolute foe.
According to Australian military historian, John Laffin, the campaign “was arguably the most arduous fought by any Allied troops during World War II”.