The Australian Army is the principal land warfare force of Australia, a part of the Australian Defence Force (ADF) along with the Royal Australian Navy and the Royal Australian Air Force. The Army is commanded by the Chief of Army (CA), who is subordinate to the Chief of the Defence Force (CDF) who commands the ADF. The CA is also directly responsible to the Minister for Defence, with the Department of Defence administering the ADF and the Army.Formed in 1901, as the Commonwealth Military Forces, through the amalgamation of the colonial forces of Australia following the Federation of Australia. Although Australian soldiers have been involved in a number of minor and major conflicts throughout Australia's history, only during the Second World War has Australian territory come under direct attack.

The Australian Army was initially composed almost completely of part–time soldiers, where the vast majority were in units of the Citizens Military Force (CMF or Militia) (1901–1980) during peacetime, with limits set on the regular Army. Since all reservists were barred from forcibly serving overseas, volunteer expeditionary forces (1st AIF, ANMEF, 2nd AIF) were formed to enable the Army to send large numbers of soldiers to serve overseas during periods of war. This period lasted from federation until post–1947, when a standing peacetime regular infantry force was formed and the Australian Army Reserve (1980–present) began to decline in importance.During its history, the Australian Army has fought in a number of major wars, including the Second Boer War, the First and Second World Wars, Korean War, Malayan Emergency, Indonesia-Malaysia Confrontation, Vietnam War, and more recently in Afghanistan and Iraq. Since 1947, the Australian Army has also been involved in many peacekeeping operations, usually under the auspices of the United Nations. Today, it participates in multilateral and unilateral military exercises and provides emergency disaster relief and humanitarian aid in response to domestic and international crises.