In a complex interconnected global environment, nonlinearity and powerful contingency reign supreme. Surprise is not merely probable, it is certain. As the Second World War came as a great surprise to the millions of people and hopeful governments that believed the First World War had been the war to end all wars it is probable the next great war will be unpredictable, the signals unmistakable only to future historians. Current Australian defense strategy provides for the provision of capable, agile, and potent military forces to coalition operations in support of Australian interests, and maintenance of a stable indo-pacific region and global order. Uncertainty is managed by military means postured to respond to threats as they arise to fight come-as-you-are conflicts with the forces at hand, military means that will likely prove insufficient in a great power conflict. During the Second World War, the potential defeat of Britain by Germany and Japans advance through the Pacific posed an existential threat to Australias sovereignty and way of life. Great power conflict has the potential to shatter the existing global order Australia relies upon for its security and prosperity and produce a war beyond the scale and duration of current contingency planning. Such an existential threat may necessitate a strategy of expansion to fulfill obligations to allies or defend Australian territory and regional interests. This monograph argues that in order to expand the land force to face an existential threat, Australia must be capable of raising, training and sustaining a corps in combat as part of a coalition. Through qualitative analysis, this study uses structured focused comparison method to examine the raising, training, sustaining and fighting of the Second Australian Imperial Force from 1939 to 1943 to determine relationships between policy, strategy, and defense planning.