The ritual of drinking dark rum, known as gunfire, was first described in the British book Soldier and Sailor Words and Phrases.
"Recruits in training always had 'gun fire' supplied to them, the work before breakfast being found particularly trying," the 1925 text says.
Those grim early mornings have evolved to become the gunfire breakfast, a tradition that boosts camaraderie among veterans at Anzac Day services around Australia.
Michael Tugwell, from the Albany RSL sub-branch in Western Australia, says the breakfasts give ex-service men and women a chance to catch-up.
"All too often you'll hear 'Hey you old bastard, I haven't seen you in a year'," Mr Tugwell said.
Veterans and their families enjoy a hot breakfast, with meat patties in warm rolls, and tea and coffee.
"And we still give them the rum," he said.
Dr Samantha Owen, a senior lecturer in humanities and social sciences at Curtin University, says the modern Anzac Day gunfire breakfast became popular in the 1930s.
The event may also hark back to the British military tradition of gunfire tea, when soldiers drank rum in hot black tea on Christmas Day or when they lay injured in hospital.
"The officer served it to the the ordinary soldiers in recognition of their efforts, so the gunfire tea became part of Anzac Day," Dr Owen said.
Now, a gunfire breakfast is an uplifting gathering between the solemn dawn service and the mid-morning march, Port Augusta RSL president Arno Schwarze says.
"We always have a bit of a stir, that's part of it, just a bit of banter."
The South Australian branch serves rum with milk.
"It tastes pretty horrible but quite a few of us do drink it."
Mr Schwarze says the event is a way to include and recognise everyone, like Indigenous and Indian veterans.
Teenagers are welcome to share the meal in Myrtleford, in northeast Victoria.
"I hope we get a few young people with enquiring minds wanting to understand our history and tradition," RSL branch secretary John Twyford said.
In Hillston, in western NSW, the number of RSL members has dwindled to eight and most are no longer well enough to drink rum.
But the marches are growing, says Wayne McLauchlan, of the Hillston-Ivanhoe RSL.
"There's patriotism coming back as young people's grandparents pass away. They can wear their medals and get a sense of pride.
"My son marches with my father's medals and I march with him."
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