<P> The struggle for New Guinea began with the capture by the Japanese of the city of Rabaul at the northeastern tip of New Britain Island in January 1942 (the Allies responded with multiple bombing raids, of which the Action off Bougainville was one). Rabaul overlooks Simpson Harbor, a considerable natural anchorage, and was ideal for the construction of airfields . Over the next year, the Japanese built up the area into a major air and naval base . </P> <P> The Japanese 8th Area Army (equivalent to a Euroamerican army), under General Hitoshi Imamura at Rabaul, was responsible for both the New Guinea and Solomon Islands campaigns . The Japanese 18th Army (equivalent to a Euroamerican corps), under Lieutenant General Hatazō Adachi, was responsible for Japanese operations on mainland New Guinea . </P> <P> The colonial capital of Port Moresby on the south coast of Papua was the strategic key for the Japanese in this area of operations . Capturing it would both neutralize the Allies' principal forward base and serve as a springboard for the invasion of Australia . For the same reasons, General Douglas MacArthur, Supreme Commander Allied Forces South West Pacific Area was determined to hold it . MacArthur was further determined to conquer all of New Guinea in his progress toward the eventual recapture of the Philippines . General Headquarters Southwest Pacific Area Operational Instruction No. 7 of 25 May 1942, issued by Commander - Allied - Forces, General Douglas MacArthur, placed all Australian and US Army, Air Force and Navy Forces in the Port Moresby Area under the control of New Guinea Force . </P> <P> Due north of Port Moresby, on the northeast coast of Papua, are Huon Gulf and the Huon Peninsula . The Japanese entered Lae and Salamaua, two locations on Huon Gulf, unopposed in early March 1942 . MacArthur would have liked to deny this area to the Japanese, but he had neither sufficient air nor naval forces to undertake a counterlanding . The Japanese at Rabaul and other bases on New Britain would have easily overwhelmed any such effort (by mid-September, MacArthur's entire naval force under Vice Admiral Arthur S. Carpender consisted entirely of 5 cruisers, 8 destroyers, 20 submarines 7 small craft). The only Allied response was a bombing raid of Lae and Salamaua by aircraft flying over the Owen Stanley Range from the carriers USS Lexington and USS Yorktown, leading the Japanese to reinforce these sites . </P>

Why did the japanese want to take over port moresby
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