Australia was comprised of a number of colonies till Federation in 1901.
During the Boer War 1899-1902, you can see that the different colonies made their own independent troop contributions, then all became part of Aus Commonwealth Forces in the course of the war.
You inspired me to go back and look for an old vhs tape...Breaker Morant. I think that was what the movie was based on. Perhaps Australian troops enlisted for the crown against the Bores. It's been long enough to forget the details. It's something to look forward to watching when I find it and get my player hooked up again.