Yarra was targeted because it's one of two councils which have voted not to hold citizenship ceremonies on Australia Day, January 26, out of respect for the Indigenous community.

Australia Day is celebrated with a national holiday on January 26 each year, typically with barbecues and Australian flags.

It marks the day when, in 1788, the Union Jack was hoisted at Sydney Cove to establish a British penal colony. However, since as early as 1938, Aboriginal and Torres Strait Islanders have opposed honoring a day they call Invasion Day or Survival Day.

Calls to change the date of Australia's national holiday are not new, but the vandalism of Captain Cook's statue has renewed the debate about the day and how the country remembers its colonial past.

Independent curator and historian Nicola Teffer disagrees.

"History is always under review," she told CNN.

"The recent statue de-facings are a protest about who, and what, has been left out of our history, not an erasure of that history."

A controversial plaque

The current furor over Captain Cook's statue is as much about the man as the plaque's inscription.

"Today the idea of discovery, the doctrine of terra nullius -- empty land -- that underpinned the British claim on this land and extinguished the rights of indigenous people no longer stands," he told CNN.

"It's been repudiated by our high court. The law is not trapped in an era of racial discrimination, nor should history be."

However the prime minister says the context of Captain Cook's "discovery" was obvious to him "when as a schoolboy I first read the inscription."

Conservative social and political commentator Andrew Bolt agrees, telling CNN: "(Captain Cook) discovered (Australia) in the way most adults reading the inscription would understand it: (he) discovered something unknown to the wider world, which in turn had not been discovered by Aborigines." 

'We are not the United States'

However, he isn't calling for the statues or plaques to be removed. He welcomes "creative suggestions for new statues and plaques that would enlarge the idea of who we are as a nation."

"Let's be clear -- that act of vandalism was disgraceful and unacceptable. But we are not the United States. The issue of confederate statues and the legacy of the civil war is not specifically analogous to the Australian experience. We do however have our own history of racism that we confront in our own way."

"The word 'discovery' in the colonial sense is such a hugely arrogant use of the language," he told CNN.

"You plant a flag on someone else's country and somehow it becomes yours? But I don't mind the plaque being there -- it reminds us that the job of dealing with unfinished business hasn't been done."

A City of Sydney spokesperson told CNN that while concerns about the statues have been referred to the council's Indigenous Advisory Panel, there are no plans to remove the monuments.

"In other cities such as Melbourne and Perth, additional plaques have been added to historical statues to give context to the original wording or to balance history," the spokesperson said.

Calls to 'change the date'

"I think it's an over-reaction," said Professor Dodson of the government.

"They are backing themselves into a corner because they're not even prepared to have a debate about it. What is the government afraid of? Obviously the two councils concerned have had a discussion and have come to a conclusion."

Yarra Council said it had commissioned an independent survey of 300 non-Indigenous people in the area which showed almost 79% supported a smaller, culturally-sensitive event.

"The overwhelming sentiment from our Aboriginal community is that January 26 is a date of sadness, trauma and distress. They have told us that this is not a day of celebration, but a day of mourning," said Mayor Amanda Stone.

"It's ironic that the Prime Minister has said changing the date is a national debate we need to have, yet his Government appears to be working to silence it by punishing councils for taking a stand in support of their Indigenous communities," Le Cerf said.

Bolt maintains the overall level of angst over Australia Day isn't high.

"Most Australians are not getting worked up at all. Some activists are, claiming that January 26 is distressing in reminding them of the arrival of the First Fleet, which they claim was the start of an alleged genocide, rather than of Western civilization." 

"Most seem the kind of people who will not accept a democratic decision," Bolt said.

However, the Australian Greens party, which unlike both major parties supports the #ChangeTheDate movement, believes momentum is building.

"As more and more people become aware of the distress the current date causes Aboriginal and Torres Strait Islander peoples, the more people will support the concept of change," said Senator Rachel Siewert, the party's spokesperson on Aboriginal and Torres Strait Islander issues.

Debate for another time?

Advocates of changing the date have proposed a variety of alternatives and point out that the tradition of Australia Day isn't a longstanding one. It wasn't until 1935 that every Australian state and territory adopted the term "Australia Day."

"January 26 was a proclamation of the penal colony of New South Wales, which doesn't include half the country," said Professor Dodson.

"Parts of the Northern Territory, parts of South Australia and all of Western Australia -- where I come from -- weren't included in it. And anyway, there were people here for tens of thousands of years."

Professor Dodson suggests the best way forward for Australia Day is to wipe the slate clean.

"I think we should wait until the day we choose to become a republic," he said.