Australia divided, page-137

bellcurve wrote - "If you ever travel overseas try to make it to Turkey and Gallipoli, where the question inevitably arises what on Earth were Australians doing there."

INHO - anybody from "...Turkey and Gallipoli..." who has to ask that question is not reading their own history.
Turkey sided with the Central Powers in WW1 so they were a legitimate target for the Allies. A German General Otto Liman von Sanders was organising the Turkish Army.
This Wikipedia page provides some history  -
https://en.wikipedia.org/wiki/Otto_Liman_von_Sanders

The German Navy was involved too through delivering a battle cruiser and a light cruiser to Turkey in July-August 1914. See - Pursuit of Goeben and Breslau
https://en.wikipedia.org/wiki/Pursuit_of_Goeben_and_Breslau

There seems little doubt that the British Empire had legitimate reasons fighting Turkey.