The Australian Labor Party split of 1916 occurred following severe disagreement within the Australian Labor Party over the issue of proposed World War I conscription in Australia. Labor Prime Minister of Australia Billy Hughes had, by 1916, become an enthusiastic supporter of conscription as a means to boost Australia’s contribution to the war effort. On 30 August 1916, he announced plans for a referendum on the issue (the Australian plebiscite, 1916), and introduced enabling legislation into parliament on 14 September, which passed only with the support of the opposition. Six of Hughes’ ministers resigned in protest at the move, and the New South Wales state branch of the Labor Party expelled Hughes. The referendum saw an intense campaign in which Labor figures vehemently advocated on each side of the argument, although the “no” campaign narrowly won on 14 November.
Even after the results of the plebiscite were made known, Hughes continued to push his position on conscription which created further tensions and division within the Labor party. The result was a split in the government, with Hughes walking out with 24 other Labor members to form a minority government under as the National Labor Party and with the support of the opposition, the Commonwealth Liberal Party.
With the war dragging on, Hughes began negotiations with opposition leader Joseph Cook to turn their confidence-and-supply agreement into formal party unity. That February, at the urging of the Governor-General the two groups formally merged to form the Nationalist Party, with Hughes as leader and Cook as deputy leader. The new party was dominated by former Liberals, and as such was basically an upper- and middle-class party. However, the presence of many former Labor men—many of whom had been early leaders in that party—allowed the Nationalists to project an image of national unity.
In May of 1917, the Prime Minister was faced with a federal election, the first under a new party which included large numbers of his former opposition.