Yes, we do need to state the obvious, if your ancestor served in the Navy or Air Force; you are seeking advice from the wrong site. However, remember that in the First World War the Australian Flying Corps, which flew fighter, bomber and reconnaissance aircraft, was part of the Army.
Before 1901 each colony maintained its own military forces. The records of people who served in these forces will be found in the appropriate state archive.
Until 1870, British Infantry Regiments garrisoned the Australian colonies. Even after that date, specialists, such as Royal Artillery and Royal Engineers supported the colonial forces.
Numbers of British officers and soldiers joined the various colonial units as they were raised, especially in time of perceived defence emergency. The colonial or Australian Army records may refer to prior British service, but details will have to be sought from British records. To get started, try the Army Museums Ogilby Trust (UK).
The Australian Military Forces from 1903 to 1948 was largely a militia army with a very small regular cadre. Except for a period after the 1929 Depression, there was universal conscription for the Militia, for service in Australia only. The Militia was also known as the Citizen Military Forces.
When a force was required to deploy overseas, in 1914 and again in 1939, a special force known as the Australian Imperial Force (AIF), liable for service anywhere in the world, was raised by voluntary enlistment for the duration of the war. The force raised in 1914 was known as the AIF. When another force was raised in 1939 it was called the Second AIF, with the original force then becoming the First AIF.
Before starting your search, assemble as much evidence as you can. You should know the full name and date of birth of the person you are researching. Ideally, have the person's service number. This should appear on any military paperwork you have on the person. The service number, initials and surname of the recipient should be stamped on the rim of any medals the person was awarded, including service medals. For some reason some men joined the First AIF under an assumed name. This was often later sorted out, but if you have the person's medals, check the rim.
South African War (Boer War) 1899 - 1902
Those who served in the South African War (Boer War) from 1899-1901 served in various colonial contingents. Only those who enlisted after 26 January 1901 into one of the contingents of the Australian Commonwealth Horse actually served in the Australian Army.
The records of those who served in colonial contingents (Queensland Mounted Infantry, Victorian Mounted Rifles, NSW Lancers, various drafts of Imperial Bushmen etc) should be located in the relevant State Archives. You may find that personal files, in the post 1914 sense, were not kept in colonial military forces. You will have to enquire at the relevant Archives about how you can search.
A number of these men did not immediately return to Australia following their tour of duty, and enlisted in local South African units such as the Bushveldt Carrabineers.
Records of members who served with The Australian Commonwealth Horse (ACH) are held by National Archives of Australia.
The Great War (The First World War) 1914 - 1919
By 1914 the Australian Army was based on a conscript Militia force that could not be required to serve outside Australia. In order to meet the intense public response to support the "Mother Country", a special volunteer force had to be raised for unrestricted service. This became the Australian Imperial Force.
The AIF was initially raised on a Regimental basis. Officers did not have service numbers. Within each Battalion the numbers stated at 1 and worked up in the order that recruits were enlisted.
The personal files of the First AIF are now on line at National Archives of Australia. Go to the National Archives web site and click on Record Search which is carefully hidden at the top right of the page, above the pictures. Log in as a Visitor. Once in Record Search, use the person's name, in the order Surname, Given Names (eg Smith, John Frederick) as key words. The Service Number, if know, can be included as a discriminator. The date range is 1914 - 1918. This should bring up the record. Once opened it can be read online or printed out.
The Second World War 1939 - 1945
In 1939 the Australian Army was still based on a conscript Militia force that could not be required to serve outside Australia. A Second AIF was raised, but the training of the Militia could not be ignored, due to the still latent threat from Japan. Militia Army numbers had a prefix indicating the state of enlistment (Q for Queensland, V for Victoria etc). In the AIF an X to indicate AIF was added to the number, thus QX1234 etc. AIF units that had corresponding units in the Militia were given a 2/ prefix, eg 2/31st Bn to avoid confusion with 31st Bn in the Militia.
When the Pacific War broke out the Australian Government was faced with a direct threat to her Northern Shores. Accordingly, the ALP, then in power, modified its opposition to conscripts serving overseas and permitted service in a defined area that included Papua New Guinea, some of the islands north and north west of Papua New Guinea and a small part of the Netherlands East Indies around Merauke. The zone was later extended to include parts of the Netherlands East Indies, but in practice usually only AIF formations were committed outside the area of what had been the Australian Territory of Papua and the Mandated Territory of New Guinea.
At this stage the Australian Army was, in fact four separate armies, each with separate conditions of service. There was the Permanent Military Force (PMF), those Regulars who had not been transferred to the AIF. There was the Second AIF, volunteers for service world wide. There was the Citizen Military Forces (CMF), partly conscripted and liable for service only in Australia and the defined area in the South West Pacific. There was also the Volunteer Defence Corps (VDC), modelled on the British Home Guard, and run by the RSL. In February 1942 the VDC was made part of the CMF, but with different conditions of service.
Later in the war, if 65 per cent of the members of a Militia battalion volunteered for the AIF the unit was redesignated as AIF, with the prefix (AIF), eg 24 Bn (AIF). This process on occasion required the transfer of units between formations and the transfer of individuals between units.
Personal files for soldiers who served in the Second World War are held by the National Archives. To search for a record, go to the National Archives website and click on Record Search which is carefully hidden at the top right of the page, above the pictures. Log in as a Visitor. Once in Record Search, use the person's name, in the order Surname, Given Names (eg Smith, John Frederick) as key words. The Service Number, if know, should be included. Surname and number will usually be sufficient. The date range is 1939-1945. This should bring up the record. A copy of the record can be ordered on line (not a free service) or the document can be called forward to the reading room in the repository where it is held. You can visit the reading room on the agreed day and read the file.
British Commonwealth Occupation Force (Japan) & Korean War
Personal files for the British Commonwealth Occupation Force (BCOF) and Korea are held at the Central Army Records Office (CARO). CARO is in the early stages of digitising these files, but for the moment all enquiries should be directed to CARO (see below).
Note: A special force was raised for service in Korea, Korea Force or KFOR. This term may show up on your relative's records. Essentially it was enlistment specifically for service in Korea, with discharge shortly after return to Australia
Conflicts Since 1953
Personal files for all conflicts since 1953 are held at the Central Army Records Office (CARO).
CARO also holds records for members who enlisted or were commissioned into the Regular Army from 1948, including those who did not see active service.
All enquiries should be directed to:
Central Army Records Office
GPO Box 393
MELBOURNE VIC 3001
or email to: firstname.lastname@example.org