The "Brisbane Line" was a defence proposal supposedly formulated during World War II to concede the northern portion of the Australian continent in the event of an invasion by the Japanese. Although a plan to prioritise defence in the vital industrial regions between Brisbane and Melbourne in the event of invasion had been proposed in February 1942, it was rejected by Labor Prime Minister John Curtin and the Australian War Cabinet. An incomplete understanding of this proposal and other planned responses to invasion led Labor minister Eddie Ward to publicly allege that the previous government (a United Australia Party-Country Party coalition under Robert Menzies and Arthur Fadden) had planned to abandon most of northern Australia to the Japanese.
Ward continued to promote the idea during late 1942 and early 1943, and the idea that it was an actual defence strategy gained support after General Douglas MacArthur referred to it during a press conference in March 1943, where he also coined the term "Brisbane Line". Ward initially offered no evidence to support his claims, but later claimed that the relevant records had been removed from the official files. A Royal Commission concluded that no such documents had existed, and the government under Menzies and Fadden had not approved plans of the type alleged by Ward. The controversy contributed to Labor's win in the 1943 federal election, although Ward was assigned to minor portfolios afterward.