3. The Battle of Midway in June 1942- US and Japanese carrier fleets fought in the central Pacific Ocean. The Japanese losing four carriers to the US's one and had to put off their plans to take control of New Caledonia, Fiji and Samoa.
This made it even more important for Japan to seize Port Moresby. But because of all the carriers the had lost, a sea operation was now not possible and they were ordered to drive over the ranges to Port Moresby. The decrease of the Japanese attack plans indicated that the tables were beginning to turn, although the Japanese were still capable of a deadly attack.
Although some Australian troops were already in New Guinea, after the Battle of the Coral Sea, the Australian military bases at Port Moresby were heightened from one militia brigade to two and shortly after another militia brigade was sent to Milne Bay to protect the airfield that was being built there. Not long after that there was news that the Japanese might land a small force at Buna. When General Douglas MacArthur, the commander in chief for Allied South West Pacific areas, heard of this, he ordered the commander of the New Guinea Force to send troops across the Kokoda Track to secure Buna.
The ranges they were talking about and the key to Japan's attack, were the Owen Stanley Ranges which started in Buna on the north coast of Papua and went up the slopes to Kokoda. The track was approximately 160km long over a series of ridges, each a little higher than the previous, until reaching 7,000 feet , then declining to 3,000 feet. It was covered in thick jungle, short trees and tall trees with vines.
On the night of the 21st of July, the Japanese landed in Buna, just as the 39th militia Battalion began to move there from Port Moresby. But General MacArthur did not take the Japanese threat seriously, as he believed that when the US Marines landed at Guadalcanal on the 7th August, the Japanese would withdraw from Buna.