Following simultaneous attacks on territories across the western Pacific in December 1941, Japan began a campaign of colonial expansion for resources in the region, aiming to take advantage of the European colonial powers’ thinly spread military reserves. On 23 January the Japanese overran the Australian-held port of Rabaul, an important staging post for the planned invasion of Port Moresby under Operation MO. A devastating Japanese air raid on Darwin on 19 February weakened Allied attack capabilities against enemy forces landing in Papua New Guinea. An aerial offensive from a US carrier strike force failed to stop the Japanese invasion of the Salamaua–Lae area and tensions finally reached breaking point with the Battle of the Coral Sea from 4–8 May. The battle was fought solely using carrier based aircraft and, although the Americans suffered greater losses, including the carrier Lexington, the Japanese invasion of Port Moresby was successfully thwarted.
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