The British Armed Forces accept citizens of all Commonwealth nations (whether a Dominion, or just in the Commonwealth of Nations), as well as citizens of nations who may no longer be in the Commonwealth, but were at the time of the individual's birth (for example, a citizen of Zimbabwe could join the Royal Army so long as they were born prior to Zimbabwe's withdrawal from the Commonwealth of Nations). So, your short answer would be yes.
You can join if you are an Australian citizen.
If what?
Yes, a person can join the Australian army, regardless of their nationality, provided the are holders of an Australian Permanent Residence visa.
A British citizen can join the US Army, and a British soldier might be attached temporarily to a US unit, or sent to a US training/instructional programme, but they won't be able to be in both services simultaneously.
Army Soldier more experience.
You need to be a Permanent Resident, and satisfy other ADF entry criteria to join the Australian Army.
How do Get enrolled in the British Army when I am from another country? What are the requirements of being in the British Army? Will I get a chance to be recruited in the British Army?
You should only join the British Army regiment that you think is best to suit your life.
A British Civilian can join the army at aged 16 years old. But he/she must have left school first
Only Australian citizens can join the Australian army. www.defencejobs.gov should answer all questions about the army and its jobs
Inorder to join either army you must be a valid citizen
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