The Australian Army is Australia's military land force. It is part of the Australian Defence Force (ADF) along with the Royal Australian Navy and the Royal Australian Air Force. While the Chief of Defence (CDF) commands the Australian Defence Force (ADF), the Army is commanded by the Chief of Army (CA). The CA is therefore subordinate to the CDF, but is also directly responsible to the Minister for Defence. Although Australian soldiers have been involved in a number of minor and major conflicts throughout its history, only in World War II has Australian territory come under direct attack.

The Australian Army's mission is to provide a potent, versatile, and updated army to promote the security of Australia and protect its people. Further, the army's key doctrine publication, The Fundamentals of Land Warfare, states that "the Army’s mission is to win the land battle".

The history of the Australian Army can be divided into two periods:

During its history the Australian Army has fought a large number of major wars, including: Second Boer War (1899–1902), First World War (1914–1918), the Second World War (1939–1945), Korea War (1950–1953), Malayan Emergency (1950–1960), Indonesia-Malaysia Confrontation (1962–1966), Vietnam War (1962–1973) and more recently in Afghanistan (2001 – Present) and Iraq (2003 – 2009). However, since 1947 it has also been involved in many peacekeeping operations, usually under the auspices of the United Nations. The largest one began in 1999 in East Timor. Other notable operations include peacekeeping on Bougainville and in the Solomon Islands, which are still ongoing to this day. Humanitarian relief after 2004 Indian Ocean earthquake in Aceh Province, Indonesia, Operation Sumatra Assist, ended on 24 March 2005.