The Last Post is played at an ANZAC Day ceremony in Port Melbourne, Victoria. Similar ceremonies are held in most suburbs and towns.

On 1 January 1901 federation of the colonies was achieved after a decade of planning, consultation, and voting.[64] The Commonwealth of Australia was established and it became a dominion of the British Empire in 1907. The Federal Capital Territory (later renamed the Australian Capital Territory) was formed in 1911 as the location for the future federal capital of Canberra. Melbourne was the temporary seat of government from 1901 to 1927 while Canberra was constructed.[65] The Northern Territory was transferred from the control of the South Australian government to the federal parliament in 1911.[66] In 1914, Australia joined Britain in fighting World War I, with support from both the outgoing Liberal Party and the incoming Labor Party.[67] Australians took part in many of the major battles fought on the Western Front.[68] Of about 416, 000 who served, about 60, 000 were killed and another 152, 000 were wounded.[69] Many Australians regard the defeat of the Australian and New Zealand Army Corps (ANZACs) at Gallipoli as the birth of the nation—its first major military action.[70][71] The Kokoda Track campaign is regarded by many as an analogous nation-defining event during World War II.[72]

Britain's Statute of Westminster 1931 formally ended most of the constitutional links between Australia and the UK. Australia adopted it in 1942, [73] but it was backdated to 1939 to confirm the validity of legislation passed by the Australian Parliament during World War II.[74][75] The shock of the UK's defeat in Asia in 1942 and the threat of Japanese invasion caused Australia to turn to the United States as a new ally and protector.[76] Since 1951, Australia has been a formal military ally of the US, under the ANZUS treaty.[77] After World War II Australia encouraged immigration from Europe. Since the 1970s and following the abolition of the White Australia policy, immigration from Asia and elsewhere was also promoted.[78] As a result, Australia's demography, culture, and self-image were transformed.[79] The final constitutional ties between Australia and the UK were severed with the passing of the Australia Act 1986, ending any British role in the government of the Australian States, and closing the option of judicial appeals to the Privy Council in London.[80] In a 1999 referendum, 55 per cent of Australian voters and a majority in every Australian state rejected a proposal to become a republic with a president appointed by a two-thirds vote in both Houses of the Australian Parliament. Since the election of the Whitlam Government in 1972, [81] there has been an increasing focus in foreign policy on ties with other Pacific Rim nations, while maintaining close ties with Australia's traditional allies and trading partners.[82]