Final answer:
The formation of the Commonwealth of Australia on 1 January 1901 marked the federation of the six Australian colonies and the introduction of the White Australia Policy aimed at restricting non-European immigration.
Step-by-step explanation:
On 1 January 1901, the six colonies of Australia unified to form the Commonwealth of Australia, marking the birth of modern Australia as a federated nation. This event is known as the Federation of Australia. The newly formed federal government allowed for the continuation of individual state legislative powers while operating under a commonwealth system with the British monarch as the ceremonial head of state. In addition, 1901 is significant for the introduction of the White Australia Policy, which through the Immigration Restriction Act, aimed to limit immigration to primarily Europeans, greatly affecting Asians and Pacific Islanders with measures such as a dictation test designed to exclude non-Europeans.