This is all despite key battles including the Battle of Milne Bay where the Japanese suffered from the first defeat of a land battle at the hand of an Australian Brigade and the Kokoda Campaign where the Australians prevented the Japanese reaching Port Moresby on the Australian Territory of Papua New Guinea in late 1942. The Australian townships of Darwin and Broome were attacked a number of times by air as well and the fact that Sydney Harbor was also attacked by two midget submarines certainly would have given the view to the Australians and Americans that the Japanese were considering invasion as a strong possibility. The strong possibility of an invasion by Japan also supported the strategic planning of the Brisbane Line.