In the wake of Federation, the defence needs of the new nation became a major preoccupation of Australia's politicians and leaders of public opinion. Although Melbourne was the national capital, the pressure for a citizen army was weaker than in Sydney, perhaps because the anti-war movement had been more organised here during the Boer War. The Victorian branch of the Australian National Defence League, the chief lobby group for universal military training, and the Political Labour Council of Victoria both favoured voluntarism. Nevertheless, in 1911, the city's boys and young men between the ages of 12 and 25 commenced training under the Defence Act Amendment Act 1909, which introduced compulsory service for the defence of Australia only. Cadet training began at age 12 with 90 hours spread over the year; at 14, it increased to four whole days, 12 half days and 14 evening sessions; and from 18 to 25, youths became members of the Citizens' Military Forces (Militia) and had to report for duty on 16 days a year, half of which had to be in camp. Opposition to the training of those under 18 came from the Victorian Socialist Party, Melbourne pacifists and women's organisations, especially when over 5000 teenage boys nationwide were imprisoned for refusing to do service, some in solitary confinement in military barracks.
The scheme operated during World War I but, led by the Melbourne-centred Australian Peace Alliance and the Women's Political Association and Peace Army as well as the city's Catholic Archbishop, Daniel Mannix, opponents of conscription defeated two referendum proposals to extend compulsory service outside Australia. Attitudes to conscription in Melbourne were more clearly associated with class and party than in the other capitals - the Universal Service League comprised only Liberals and academics, unlike Sydney, where it was cross-party, and the split in the Australian Labor Party (ALP) and trade union movement was smallest in Victoria.
The compulsory training scheme was abandoned by the Scullin Labor Government in 1929. When wartime conscription was reintroduced by John Curtin's Labor Government in 1943, including service outside Australia as far north as the Equator, the main opposition came from Victorian pacifist and labour circles, MHR Maurice Blackburn quitting the Party over the issue. Conscription for domestic purposes, introduced late in 1942, applied to all men aged 16 to 65 and to all single and divorced women without dependent children. It too was staunchly opposed by the Victorian labour movement, but neither domestic nor military conscription aroused the widespread hostility it had done during World War I.
Compulsory training, called national service, was reintroduced by the Menzies' Liberal Government in the Cold War context of 1951 but abandoned in 1959. It did not rouse the same level of opposition as the earlier or later schemes. On 10 November 1964, Menzies introduced a selective system of conscription that specifically included liability for overseas service: all 20-year-olds had to register and those whose birthdates were drawn out of a lottery barrel (about one in 10) were expected to train for two years. Five months later, the government decided to send 1000 combat troops to South Vietnam, which in March 1966 was upgraded to 4500, including 500 national servicemen. Once again, national resistance was centred in Melbourne, culminating in the moratorium movement led by MHR Jim Cairns; numbers gathering in the city's streets on 8 May 1970 were more than twice the number of any other centre. It was in Melbourne too that draft resister Barry Johnston ran an underground campaign in the 1972 federal elections as the endorsed ALP candidate for Hotham. Within days of its election in December 1972 the new federal Labor Government announced the end of conscription and it has not operated in Australia since.