At Wikipedia, https://en.wikipedia.org/wiki/And_the_Band_Played_Waltzing_Matilda#Historical_accuracy
it says,

"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 in Europe were volunteers, and the government did not force conscripts to fight overseas.

"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.

"The vast majority of the 16,000 Australian and New Zealand troops landed not at Suvla but at Anzac Cove, 8 kilometres to the south, and some 15 weeks earlier. 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. Bogle states that he substituted "Suvla" for "Anzac" because at the time he wrote the song (1971) there was 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."