The parade took an hour to file into the arena in front of the memorial. There were banners representing every aspect of Australian military involvement over more than a century.

Some frail veterans from World War 2 were conveyed in open-backed Land Rovers from the period. Three fighter planes roared over the parade in tribute.

The ceremony began with the entry of a riderless military horse called "Boy". In his stirrups were boots facing backwards to symbolise a warrior - his rider - who didn't return alive.

There was a protest at the edge of the ceremony by Aboriginal people who thought that the "Frontier Wars" between their ancestors and white settlers should also be acknowledged.

The dissident marchers walked unofficially at the end of the veterans' march but were then barred from entering the closed off area where the formal ceremony happened.

One of the protesters, Wannganar, said, "We are just making people aware that we did fight in the wars but our people never got humane treatment.

"It really makes me angry. No matter what you do, you'll still be a nobody."

Another protester, Lydia George, said, "My father served in the war in Malaya and I'm here because I share the sorrow of what has happened to our people."

In the official ceremony itself, Wing Commander Jonathan Lilley, a member of the Worimi people, played a haunting rendition of Indigenous music on the didgeridoo.

This was Sir Peter Cosgrove's last Anzac Day in his role as Governor-General because his term ends in June.

With flags at half-mast behind him, the former defence force chief sought to explain to youngsters and service first-timers the significance of the day.

"In the gamut of motives from the profoundly philosophical to simple curiosity, there is a fundamental reason," he told the crowd in Canberra.

"It is by our presence to say to the shades of those countless men and women who did not come home or who made it back but who have now passed and to say to their modern representatives, the ones around the nation who today march behind their banners.

"You matter. What you did matters. You are in our hearts. Let it be always thus."

Read more: The story behind Canberra's Anzac Parade

He paid tribute to the tens of thousands of people who never returned home, saying they were "gone but not forgotten".

It is for those souls that veterans march, he added.

"When we march we like to look at those gathered to watch and wonder, young and old, family, friends and strangers and to catch their gaze and convey our silent message," Sir Peter said.

"We did it for our nation, for what Australia stands for, we did it for you. Let it be always thus."

More than a dozen wreaths were laid following Sir Peter's address, including by government minister Simon Birmingham on behalf of Prime Minister Scott Morrison.

After the ceremony, the Director of the Australian War Memorial, Dr Brendan Nelson, said, that about 10,000 people attended the day time ceremony in addition to 35,000 at the Dawn Service.

He said, "The large crowd in attendance at the Anzac Day National Ceremony speaks to our nation's respect for those who serve and the families who love them."