The paper focuses on the initial stage of the formation of the Commonwealth of Australia, and the process of its establishing as an independent State. The international political context for the development of the country, from the period of creation of the Federation to the beginning of the Second World War, is primarily viewed. The Commonwealth’s international position, its place and role in the regional and global geopolitical processes of the early XX century, in particular in the context of its relations with Great Britain, are analyzed. The features of the transformation of British colonial policies on the eve of the First World War are examined. The specifics of the UK system of relations with Australia, as well as other dominions, are being examined. The features of status of the dominions in the British Empire system are shown. The role of the dominions and, in particular, the Commonwealth of Australia in the preparatory process for the First World War, as well as the peculiarities of its participation in hostilities, is analyzed. The significance of the actions of the First World War on the domestic political situation in Australia, as well as its impact on dominions relations with the British Empire, is revealed. The history of the foundation of the Australian-New Zealand Army Corps (ANZAC) and its participation in imperial forces on the frontline of the First World War is analyzed. The success and failure of its fighters, as well as the role of ANZAC, in the process of formation an Australian political nation are analyzed. The economic, humanitarian and international political consequences of the First World War for the Commonwealth of Australia are examined, as well as the influence of these consequences on the structure of relations between the dominions and the British Empire. The socio-economic situation of the Commonwealth of Australia on the eve of World War II, in particular the impact of the Great depression on the development of the country as a whole and its internal political situation in particular, is analyzed. The ideological, military-strategic and international political prerequisites for Australia’s entry into the Second World War are being considered.