I think it was a defining moment in our history. We were a young country (Federation was in 1901, Gallipoli was in 1915) and this was the first time we fought as a country, not as a bunch of colonies. It was our first serious loss (of battle and life).

We fought under our own flag, and the Aussie soldiers annoyed the crap out of the Generals with their irreverence to rank and apparent lack of disciplin. But the Diggers got stuck in and did the job.

Gallipoli was a starting point, even though we had our arses kicked there. That was when we said to the world "We're bloody Australians, mate."