On 26 January 1838, a group of mounted police under the instruction of the colonial government led a surprise attack on a camp of Kamilaroi people at Waterloo Creek in northern New South Wales, killing at least 40.

It was the 50th anniversary of the planting of the Union Jack in Sydney Cove. As the massacre took place, a celebratory regatta was held in Sydney, 480km away, to mark the colony’s jubilee.

One hundred years later, on 26 January 1938, a date by then called Australia Day, a group of 100 mostly Aboriginal and Torres Strait Islander peoples, led by the Aborigines Progressive Association, met at Australian Hall in Sydney for a day of mourning protest and passed a resolution calling for equal rights. On the harbour, the city welcomed tall ships to mark the sesquicentenary of British colonisation.

The day of mourning began an annual tradition of protest. By the time of the bicentenary celebrations in 1988, 50,000 people from all over Australia came together in Sydney for “the long march for justice, freedom and hope”.

Michael Anderson, a Kamilaroi man and one of the founders of the Aboriginal tent embassy in 1972, was more blunt on its message: “It was about the fact that they stole our land.”

The celebration of Australia Day has always been fraught. The mounting push to change the date has dominated headlines in January for the past few years, and this month led to the prime minister, Malcolm Turnbull, declaring himself “disappointed” in anyone who supported shifting the national holiday.

The campaign, Turnbull said, would “take a day that unites Australia and Australians and turn it into one that would divide us”.

“A free country debates its history, it does not deny it.”

His comments drew criticism from Aboriginal and Torres Strait Islander peoples, who say 26 January has always been a divisive date based on a selective celebration of history.

To claim it as a day of unity is to remember the regatta and not the massacres; to mark the official celebrations and not the protests that occurred alongside them.

Indigenous protesters gather at the meeting on 26 January 1938, which demanded full citizens’ rights. Photograph: State Library of NSW/a429004h

“A lot of stuff gets erased in order to celebrate this nation,” Celeste Liddle, an Arrernte writer and union organiser, says.

Liddle is one of the organisers of the Melbourne Invasion Day march, which was attended by more than 20,000 people last year. An even bigger crowd is expected this Friday, with similar marches held in every state and territory.

It is the work of grassroots Indigenous activists, standing on the shoulders of an opposition to occupation that dates back 230 years to the arrival of the first fleet.

Thousands march through Melbourne on 26 January 2017 to raise awareness of Indigenous rights and protest the celebration of Australia Day/Invasion Day. Photograph: Chris Hopkins/Getty Images

“To celebrate Australia Day requires a denial of history,” Liddle says. “It requires a denial not just of the fact that it was invasion, that sovereignty was never ceded by Indigenous groups … We’re not actually talking about those things in any great detail in the context of the country.

“I don’t see Turnbull engaging in those sorts of debates, I see him actively trying to avoid them.”

The Waterloo Creek massacre is one of 150 mass killings recorded in a mapping project by the University of Newcastle. The entry lists the motive as “opportunity”.

We’re opposed to our invasion being celebrated Celeste Liddle

Major James Nunn had left Sydney several weeks earlier with instructions from the acting governor, Lieutenant-Colonel Kenneth Snodgrass, to track down Aboriginal people who had reportedly killed five stockmen in separate incidents on the new pastoral runs on the Gwydir river, and “use the utmost exertion to suppress these outrages”.

Nunn rode with 20 troopers and two sergeants. On the morning of 26 January, after pursuing a group along the Namoi for three weeks, they were attacked by men armed with spears.

The troopers gave chase and found the camp a mile upriver at Waterloo Creek. Nunn’s two sergeants were later questioned at an inquiry in Sydney. One, who rode at the back of the group, said four or five Aboriginal people were killed. The other, who rode at the front, listed the death toll as 40 or 50.

The troopers were “welcomed like heroes” on their return journey to Sydney, the Australian Museum notes. The official inquiry was dropped.

It was just six months before the Myall Creek massacre, where 11 stockmen rounded up and slaughtered a group of 30 Aboriginal men, women and children. After two trials, and a fierce public debate over whether the killing of Aboriginal people was even considered a crime, seven stockmen were hanged.

An anonymous correspondent to the Australian newspaper, published on 8 December 1838, claimed that one of the jurors who acquitted the men at the first trial had said: “I know well that they were guilty of the murder, but I, for one, would never see a white man suffer for shooting a black.”

Poster advertising the 1938 day of mourning. Photograph: Couresty of Australian Institute of Aboriginal and Torres Strait Islander Studies

Changing the date of Australia Day won’t change that history or other injustices done to Australia’s first peoples, but supporters of the movement say it would acknowledge that the establishment of modern Australia was more contested and bloody than the national mythology has previously held.

Both the government and the opposition have used the immutability of history as an argument for continuing to celebrate Australia Day on 26 January, because to do otherwise would be a denial of history.

Aboriginal and Torres Strait Islander views on Australia Day range from acceptance to abolition, with those who want to change the date occupying a broad swath in the middle.

Liddle says that if the full spectrum of Australia’s post-1788 history was acknowledged, including the many and ongoing injustices to Aboriginal and Torres Strait Islander peoples, Australia Day would not be celebrated at all. It’s a catalogue of issues that shifting a public holiday will not fix.

“Aboriginal people don’t march because we’re unhappy with the date of celebration,” she said. “We march because we’re strongly opposed to our invasion being celebrated … Just changing the date is not going to address the deep social issues that we’re fighting for here.

“I think that people who are promoting the change the date thing need to be really really cautious that it’s not just the changing of a nationalistic celebration to another day without concern for the real reasons why it is that we’re out there.”

Labor MP Linda Burney, the first Indigenous woman elected to the federal House of Representatives, had a similar concern. She said a recent push by the Australian Greens to encourage local governments to support changing the date, following a number of councils voting in 2017 to move their celebrations to a less contentious day, was “a very narrow way to look at the issue of Indigenous affairs”.

We can’t undo history but the naming and the celebrating of us as a unified nation ... the 26th isn’t that day Rod Little

Instead, she said, the focus should be on making progress to implement the ideas in the Uluru Statement, the principal recommendation of which was rejected by the Turnbull government in October for being unpalatably ambitious.

Burney, echoing Labor party policy, does not support changing the date, but says 26 January is a day of reflection to “think deeply about the truth and true history of this country”.

Meriki Kalinya, a Gunnai-Gunditjmara woman and one of the Victorian convenors of the Warriors of the Aboriginal Resistance, a grassroots activist group behind the resurgence of large-scale Invasion Day rallies, is an abolitionist.

The organisation was founded in Brisbane ahead of the 2014 G20 summit and held its first national Invasion Day rallies in 2015.

Kalinya says the change the date campaign has brought more non-Indigenous people on to the street to join Invasion Day marches, but it should not coopt their original purpose, which was to call attention to substantive rights-based issues, such as land rights, reparations, deaths in custody and the call for a treaty.

“[Changing the date] would just be a feelgood thing that will pacify the masses and as soon as the date is changed, no one will want to talk about what is really happening,” she says. “If politicians are caught up with white Australians’ feelings, we will just get token gestures like Sorry [the national apology to members of the stolen generation] in 2008.”

Rod Little, a Yamatji and Wadjuk man and co-chair of the National Congress of Australia’s First Peoples, supports changing the date.

“We can’t undo history but the naming and the celebrating of us as a unified nation ... the 26th isn’t that day,” Little says.

National Congress is a peak representative body for Aboriginal and Torres Strait Islander organisations. Initial responses to a survey of its members last week found that 83% supported changing the date and 50% said doing so was important for reconciliation.

The Indigenous affairs minister, Nigel Scullion, said last week that no Indigenous person had raised the issue of changing the date of Australia Day with him. Little says perhaps that was because he had not bothered to ask.

“When people are steadfast on not changing the date, they are either not having the conversation or are not prepared to have the conversation, and for me that might come from their position of privilege,” Little says.

He says support for changing the date comes from a growing awareness of the full history of Australia, including atrocities and injustices done to Aboriginal and Torres Strait Islander peoples.

Naming an alternative date is more challenging, which is one of the reasons Liddle and others advocate abolition rather than change. Australia has yet to do anything that could be marked by a unified celebration, she says.

“When you have got a country whose constitution is based on the idea of terra nullius, celebrating that is never going to sit right with Aboriginal people,” she says. “Recognising sovereignty and moving toward some kind of agreement, that would be something worth celebrating.”