As a dominion of the British Empire, Australia automatically entered the First World War when Britain declared war on Germany at 11pm on 4 August 1914 London time (8am 5 August Melbourne time). In the weeks beforehand, both sides of parliament had pledged full support for Britain. At a meeting at Colac in Victoria on 31 July, the opposition leader Andrew Fisher announced that ‘Should the worst happen … Australia will stand beside [Britain] and help defend her to our last man and last shilling’. When the news reached Australia on 5 August, the Prime Minister Joseph Cook stated that ‘when the Empire is at war, so is Australia’.
Read more about Australia's involvement in the First World War.