However, the 51st Division, including the army's commander, Hatazō Adachi, and his senior staff, came under Allied air attack while en route from their supply base at Rabaul to Lae, in the Battle of the Bismarck Sea.

[citation needed] Operation Cartwheel, an Allied master plan implemented from mid-1943, progressively severed the supply lines between Rabaul and frontline Japanese forces.

Key defeats included the withdrawal of the Imperial Japanese Navy from the Solomon Islands campaign, followed by landings on New Britain, as well as Aitape and Hollandia, in April 1944.

As ammunition began to run low, many of Japanese field commanders resorted to banzai charges, rather than surrender.

[4] The remnants of the Japanese 18th Army surrendered to the Australian 6th Division at Cape Wom, by Wewak, New Guinea.