The Australian Imperial Force (AIF) was the name given to all-volunteer Australian Army forces dispatched to fight overseas during World War I and World War II.
Following the Federation of Australia in 1901, the Commonwealth Military Forces were formed with a small regular army and a larger component of reservists in the Citizens Military Force (CMF). The CMF could not be deployed overseas, so the AIFs were formed in 1914 and 1939 respectively to provide troops for overseas service.
The two AIFs are distinguished by referring to the World War I contingent as the "1st AIF", and the World War II contingent as the "2nd AIF". During World War I, the Australian Flying Corps, the precursor of the Royal Australian Air Force, was part of the 1st AIF.
Members of the First AIF went on to serve in the Allied intervention in the Russian Civil War from 1917 to 1920 and many Australian First World War Memorials are to the Great War of 1914 to 1919 in recognition of this service.
The modern regular Australian Army was established in 1947 and its soldiers can be deployed anywhere in the world. Theatres where they have served include Korea, Malaya, Indonesia, Vietnam, the Persian Gulf, various Pacific nations, Afghanistan and Iraq.