Here's Wikipedia on historical accuracy, or otherwise, of And The Band Played Waltzing Matilda:

Historical accuracy
The line "they gave me a tin hat" is anachronistic, as steel helmets were not issued to British and Empire troops at Gallipoli.

Walsh (2018) suggests that the line "they marched me away to the war" implies compulsion, in the form of conscription, whereas all Australian troops were volunteers, and the government did not introduce conscription.

The song refers to the fighting at Suvla Bay in the lines:

And how well I remember that terrible day, how our blood stained the sand and the water.
And of how in that hell that they called Suvla Bay, we were butchered like lambs at the slaughter.
Johnny Turk he was waiting, he'd primed himself well, he showered us with bullets and he rained us with shell, and in five minutes flat, he'd blown us all straight to hell. Nearly blew us right back to Australia.

The vast majority of the 16,000 Australian and New Zealand troops landed not at Suvla but at, as the name implies, Anzac Cove, 8 kilometres to the south, and some 15 weeks earlier. The Suvla landing was initially successful and established a beachhead, with comparatively light casualties. Bogle states that he substituted "Suvla" for "Anzac" because at the time he wrote the song (1971) there was already a "deeply ingrained misconception" amongst Australians that all their troops had fought entirely at Suvla. He also states that it was easier to incorporate the word "Suvla" into the lyric.

(There was a small Australian presence at Suvla, the Royal Australian Naval Bridging Train, an engineering and construction unit comprising 350 men, of whom none were killed during the initial landing and two by the time the campaign was abandoned eleven months later.)