Swan by-election, 1918

The 1918 Swan by-election was a by-election for the Division of Swan in the Australian House of Representatives, following the death of the sitting member Sir John Forrest. Held on 26 October 1918, the by-election led to the election of the youngest person to be elected until 2010 to the Parliament of Australia, Edwin Corboy. It saw the conservative vote split between the Country Party and the Nationalist Party, which directly prompted the introduction of preferential voting in Australia.

Sir John Forrest, who had been the first Premier of Western Australia, was elected to the Australian House of Representatives for the Division of Swan at the first federal election on 29 March 1901.

On 6 February 1918, Forrest was offered a place in the British peerage (he was to be created Baron Forrest of Bunbury), though the relevant letters patent had not at the time been issued. Forrest set out for England to accept the offer and take up his place in the House of Lords, but he died en route on 2 September 1918, off the coast of Sierra Leone, from cancer. Thus, a by-election was called to replace Forrest as the representative for Swan.

By 1909, Australia had evolved a two-party system at the federal level, with the conservative Commonwealth Liberal Party and the progressive Australian Labor Party having both alternately won power via general election. This system was upset in November 1916, when the Labor party split over the issue of conscription; Prime Minister Billy Hughes and his pro-conscription supporters left the Labor party and formed a minority government as the "National Labor Party", before merging with the Liberals in February 1917 to form the Nationalist Party of Australia with Hughes as their leader.

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