 At the start of the war , Australia 's military forces were focused upon the part @-@ time Militia . The small number of regular personnel were mostly artillerymen or engineers , and were generally assigned to the task of coastal defence . Due to the provisions of the Defence Act 1903 , which precluded sending conscripts overseas , upon the outbreak of war it was realised that a totally separate , all volunteer force would need to be raised . The Australian government pledged to supply 20 @,@ 000 men organised as one infantry division and one light horse brigade plus supporting units , for service " wherever the British desired " . The Australian Imperial Force ( AIF ) subsequently began forming shortly after the outbreak of war and was the brain child of Brigadier General William Throsby Bridges ( later Major General ) and his chief of staff , Major Brudenell White . Officially coming into being on 15 August 1914 , the word ' imperial ' was chosen to reflect the duty of Australians to both nation and empire . The AIF was initially intended for service in Europe . Meanwhile , a separate 2 @,@ 000 @-@ man force — known as the Australian Naval and Military Expeditionary Force ( AN & MEF ) — was formed for the task of capturing German New Guinea . In addition , small military forces were maintained in Australia to defend the country from attack . 
