13 June 1942

Following their naval setbacks in the Battles of the Coral Sea and Midway, Japan’s High Command decides on an overland attack on Port Moresby, from the north coast. They order plans for forces from Rabaul to land near Buna and travel across the Owen Stanley Range, via the Kokoda Track, to Moresby.

Earlier, on 18 May, Allied secret radio intercepts had picked up a signal from Tokyo's Naval Intelligence Division: "Enemy air strength in the Australia area at present will make it impossible to keep Moresby supplied by the sea route between Rabaul and and Moresby after the latter is occupied - by means of land route - although the preparations for the occupation are complete we consider it necessary to begin the construction of a land route to Moresby from Lae."