In 1951, during the Korean War, National Service was introduced under the National Service Act, 1951. All Australian males aged 18 had to register for 176 (later 140) days of training and five years of service in the Citizens Militia Force. The regular military forces were kept as voluntary. The system was ended in 1959.
Australia's first law for compulsory military training was passed in 1911 and abolished in 1929 (with two conscription referenda during World War I being defeated). Conscription was revived briefly in 1939, but without overseas service (although 'Australia' was defined to include New Guinea). National service was reintroduced 1964 and again in May 1965. From that date until 1972, over 15,000 national servicemen fought in the Vietnam War, of whom 200 were killed and over 1,200 wounded. National Service was abolished on 5 December 1972 by the Labor government.
Australian War Memorial encyclopaedia, 'National Service Scheme', http://www.awm.gov.au/encyclopedia/conscription/vietnam.asp, and 'Conscription, http://www.awm.gov.au/encyclopedia/conscription/index.asp, accessed 15 April 2010