Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It has a land area of 7,688,287 km2 (2,968,464 sq mi), making it the sixth-largest country in the world, and is the world's flattest and driest inhabited continent. It is a megadiverse country, and its size gives it a wide varie In 1914, Australia joined the Allies in the First World War, and took part in the fighting on several fronts. Of the 324,000 men who served overseas, about 60,000 were killed and another 152,000 were wounded. Many Australians regard the defeat of the Australian and New Zealand Army Corps (ANZAC) at Gallipoli in 1915 as the "baptism of fire" that forged the new nation's identity. The beginning of the campaign is commemorated annually on Anzac Day, a date which rivals Australia Day as the nation's most important. From 1939 to 1945, Australia joined the Allies in fighting the Second World War. Australia's armed forces fought in the Pacific, European and Mediterranean and Middle East theatres. The shock of Britain's defeat in Singapore in 1942, followed soon after by the bombing of Darwin and other Japanese attacks on Australian soil, led to a widespread belief in Australia that a Japanese invasion was imminent, and a shift from the United Kingdom to the United States as Australia's principal ally and security partner. Since 1951, Australia has maintained a mutual security alliance with the United States under the ANZUS treaty. In the three decades following World War II, Australia experienced significant increases in living standards, leisure time and suburban development. Governments encouraged a large wave of immigration from across Europe and called these migrants "New Australians". High immigration was justified to Australians using the slogan "populate or perish", and from the 1960s the white Australia policy was gradually relaxed. A member of the Western Bloc during the Cold War, Australia participated in the Korean War and the Malayan Emergency during the 1950s and the Vietnam War from 1962 to 1973. Tensions over communist influence in society led to unsuccessful attempts by the Menzies Government to ban the Communist Party of Australia, and a bitter split in the Labor Party in 1955. As a result of a 1967 referendum, the federal government gained the power to legislate with regard to Aboriginal Australians, and Aboriginal Australians were fully included in the census. Pre-colonial land interests (referred to as native title in Australia) was recognised in…