Vice Admiral Inoue warns Japan's Navy General Staff of the threat from Australia as an ally of the United States

During the planning that preceded the Pearl Harbor attack, Vice Admiral Shigeyoshi Inoue (picture below) made significant contributions to Japan's strategic planning in regard to the threat from Australia as an ally of the United States. Inoue was one of Japan's better strategic thinkers, and commander of the 4th Fleet, or South Seas Force, based at Truk in Japan's Caroline Islands League Mandate. Inoue was also the commander responsible for absorbing and defeating the expected American counter-offensive against the Japanese-held Marshall and Caroline island groups.

Vice Admiral Shigeyoshi Inoue
Vice Admiral Inoue made significant contributions to Japanese strategic planning in regard to the threat from Australia as an ally of the United States. He persuaded Japan's Imperial General Staff to invade Australia's Territories of Papua and New Guinea.

Vice Admiral Inoue warned the admirals of Navy General Staff that the Americans would be likely to try to outflank Japan's eastern defensive perimeter anchored on the Marshall Islands by counter-offensives launched from Australia and the British Solomon Islands, and by using Port Moresby and Guadalcanal as forward bases. The First Operational Stage of Japan's Pacific aggression, initiated by the surprise attack on Pearl Harbor, had initially been intended to halt short of the island of New Guinea. Vice Admiral Inoue provided Navy General Staff with persuasive arguments for extending Japan's southern defensive perimeter beyond Japan's Caroline Islands to New Guinea. Inoue drew attention to the islands of the Bismarck Archipelago that form a crescent shape off the north-eastern coast of the New Guinea mainland. In 1941, the Bismarck Archipelago was part of Australia's Territory of New Guinea which was still a League of Nations Mandate. New Britain, the largest island in the archipelago, contained a fine port called Rabaul. Inoue pointed out to the admirals that Truk, Japan's main naval base in the Central Pacific, was only 1,120 kilometres (700 miles) from Rabaul. In Australian-American hands, Rabaul could be used by American B-17 heavy bombers to reach and bomb Truk. Inoue warned that to leave New Guinea and the nearby British Solomon Islands in Australian-American hands would involve a serious risk of the two Allies outflanking Japan's eastern defensive perimeter anchored on the Marshall group of islands.

The warnings made sense to the Japanese admirals, and Imperial General Headquarters agreed with Inoue that the two largest islands of the Bismarck Archipelago (New Britain and New Ireland) should be added to his list of Pacific Ocean targets in the First Operational Stage that already included Guam, Wake, and Britain's Gilbert Islands chain. Once removed from Australian control, the Japanese intended that Rabaul would become their major base in the South-West Pacific.

When occupied and fortified by Japan, Imperial General Headquarters intended that Australia's Territory of New Guinea Mandate and the British Solomon Islands (including Guadalcanal) would become sections of Japan's southern defensive perimeter. Japan would then be able to establish forward naval bases and airfields in these captured territories from which it could strike at Port Moresby on the southern coast of Australia's Territory of Papua, and most importantly, begin the process of severing Australia's lifeline to the United States. Although not widely known at the present time, Australia exercised full sovereignty over its Territory of Papua in 1942. Papua was never a League of Nations Mandate. It had been transferred to Australian ownership by Britain in 1906.

On 23 January 1942, after heavy air and naval bombardment, five thousand elite troops of Japan's South Seas Detachment stormed ashore at Rabaul and quickly overwhelmed the heavily outnumbered and poorly equipped Australian garrison.

Author's Note

An excellent introduction to Japan's Pacific War strategy can be found in Richard B. Frank's magisterial "Guadalcanal" (1990). Frank deals with the important contribution made by Vice Admiral Shigeyoshi Inoue before Pearl Harbor to Japan's strategic planning for military aggression in the Pacific, and in particular, Inoue's contributions to Japanese strategic planning to deal with the potential threat from Australia as an ally of the United States and potential springboard for an American counter-offensive. There is one major flaw in Frank's work. He speaks of Emperor Hirohito as if he was a puppet of the Japanese military. Nothing could be further from the truth. Hirohito's true role as commander in chief of Japan's military was concealed by the Japanese to protect him from prosecution as a war criminal. Professor Herbert P. Bix exposed the full extent of Hirohito's complicity in Japan's military aggression in his Pulitzer Prize-winning "Hirohito and the making of modern Japan", published in 2000.

Vice Admiral Inoue persuades Navy General Staff of the need for Japan to capture Port Moresby and the Solomons

Although he had only been authorised to capture the islands of New Britain and New Ireland in Australia's New Guinea Mandate in the First Operational Stage, Vice Admiral Inoue appreciated that a major Japanese base at Rabaul on New Britain would be vulnerable to attack by Allied bombers based at Lae and Salamaua on the northern New Guinea mainland, at Port Moresby on the southern coast of the Australian Territory of Papua, and on islands comprising the British Solomon Islands chain (including Tulagi and Guadalcanal). He urged Navy General Staff to bring the whole of the island of New Guinea (including Port Moresby) and the whole of the British Solomons under Japanese control.

Inoue supported this proposal for further extension of Japan's southern defensive perimeter with three very persuasive arguments. The first was that Japanese forward air and naval bases located at Port Moresby and Guadalcanal in the Solomon Islands chain would enable Japan to strike deeply into the Australian mainland and far out into the South Pacific to sever the lines of communication between Australia and the United States. The second was that Japanese occupation of Port Moresby and Guadalcanal would make it far more difficult for the United States and Australia to mount counter-offensives through New Guinea and the Solomon Islands. Inoue's third argument was that Port Moresby was situated on the southern coast of the New Guinea mainland, and separated from the Australian mainland by a 500 kilometre (300 mile) stretch of the Coral Sea. The capture and occupation of Port Moresby by the Japanese would deny the Allies a forward base from which to launch air attacks on Japan's newly acquired military base at Rabaul. Its capture and occupation by the Japanese would also place a large stretch of Coral Sea between Allied bombers on the Australian mainland and a wholly Japanese-occupied New Guinea. Inoue did not need to press a fourth argument for capturing Port Moresby. Senior officers in Japan's Navy General Staff were well aware of the potential for Port Moresby to provide Japan with a springboard for an invasion of the Australian mainland when that became feasible.

Inoue's argument for the capture of Australia's Port Moresby was greatly strengthened by the quick Australian response to the capture of Rabaul. The Royal Australian Air Force immediately began to bomb Japanese shipping and installations at Rabaul from airstrips at Port Moresby, Lae, and Salamaua. On 29 January 1942, Japan's Navy General Staff responded positively to Vice Admiral Inoue's arguments by ordering the Commander in Chief of Japan's Combined Fleet, Admiral Isoroku Yamamoto, to capture Lae, Salamaua, and Port Moresby on the New Guinea mainland, and Tulagi island in the British Solomon Islands chain. The Japanese captured Lae and Salamaua on 8 March 1942. Port Moresby and Tulagi were scheduled for capture in April 1942, but an air raid launched from the Gulf of Papua on 10 March 1942 by air groups from USS Lexington and USS Yorktown caught the Japanese by surprise as they were still engaged in landing troops, supplies, and equipment. The American carrier aircraft caused heavy damage to Inoue's warships and transports anchored off Lae and Salamaua. The capture of Port Moresby and Tulagi had to be postponed until May to enable Inoue's ships to be repaired or replaced. Inoue also received Admiral Yamamoto's promise that three aircraft carriers would be assigned to protect the postponed Port Moresby and Tulagi amphibious landings.