 Enlisted under the Defence Act 1903 , the AIF was an all volunteer force for the duration of the war . Australia was one of only two belligerents on either side not to introduce conscription during the war ( along with South Africa ) . Although a system of compulsory training had been introduced in 1911 for home service , under Australian law it did not extend to overseas service . In Australia , two plebiscites on using conscription to expand the AIF were defeated in October 1916 and December 1917 , thereby preserving the volunteer status but stretching the AIF 's reserves towards the end of the war . A total of 416 @,@ 809 men enlisted in the Army during the war , representing 38 @.@ 7 percent of the white male population aged between 18 and 44 . Of these , 331 @,@ 781 men were sent overseas to serve as part of the AIF . Approximately 18 percent of those who served in the AIF had been born in the United Kingdom , marginally more than their proportion of the Australian population , although almost all enlistments occurred in Australia , with only 57 people being recruited from overseas . Indigenous Australians were officially barred from the AIF until October 1917 , when the restrictions were altered to allow so @-@ called " half @-@ castes " to join . Estimates of the number of Indigenous Australians who served in the AIF differ considerably , but are believed to be over 500 . More than 2 @,@ 000 women served with the AIF , mainly in the Australian Army Nursing Service . 
