Relief and awe greeted the unearthing of human remains from a field in France where up to 170 Australian soldiers killed in World War I may lie buried.
Relief, because the discovery of a hand and arm told archaeologists digging near the July 1916 battlefield of Fromelles in northern France that they were on the right track.
And awe, because of the task that still lies ahead, said archaeologist and dig leader Dr Tony Pollard.
"It's a very complex mix of emotions," said Pollard, of Glasgow University, after the discovery that may end the mystery of what happened to the bodies of hundreds of Australian and British soldiers killed in the disastrous battle.
"We are now aware we have to work very hard and it's going to be an emotional drain."
The Australian-led excavation team working on the site was due to resume work later Wednesday (AEST) after informing French authorities of their find.
Defence, Science and Personnel Minister Warren Snowdon said in Canberra the discovery of human remains confirmed there were bodies at the Pheasant Wood site near Fromelles.
It's believed 170 Australian diggers lie buried at Pheasant Wood in mass graves dug by German troops who recovered their bodies from the battlefield.
The site may also contain the remains of up to 400 British soldiers.
But Snowdon cautioned there was nothing yet to confirm the discovery of Australian soldiers.
"The most important task for this team is to determine the condition and quantity of the remains," he told federal parliament.
Australian authorities know the names of soldiers whose bodies remain missing after the battle of Fromelles, thanks in part to German burial records.
"We will pursue every available method to identify these remains, including the use of DNA if there is a reasonable chance of a match," Snowdon said.
It's possible that those identified will be brought back to Australia.
But Snowdon added:"Should the remains be assessed as unidentifiable, the Australian government position is that the soldiers remain in situ and the land in which they lie be acquired by the Commonwealth War Graves Commission as an official war cemetery."
Pollard said no human remains would be removed at this stage, but would be carefully re-buried until a decision was made on the future of the site.
He said the bodies were believed to be in five mass graves, one of which was where the search started.
"We picked one trial excavation in one pit and spent all day ... taking it down, 20cm at a time."
Shortly before they were due to pack up for the day "lo and behold we encountered these human remains".
The battle of Fromelles was a disaster, with Australian troops mown down as they attacked strong German positions.
In 24 hours, 5,533 Australians were either killed, wounded or captured. Two thousand died.
Mr Snowdon said the dead included 12 sets of brothers, two sets of fathers and sons, plus many who had fought at Gallipoli.
"We need to understand the horror of this event," Snowdon said. "It is the worst experience (of) loss of life, the most tragic day in Australia's military history."
"Like the discovery of the wreck of HMAS Sydney, this news will be of great satisfaction for many Australian families who have never known the fate of their uncles, great uncles or grandfathers."
Prime Minister Kevin Rudd said those who died at Fromelles were heroes.
"It is very important to handle this very sensitively," he told reporters in Canberra.
Army chief, Lieutenant General Peter Leahy, said the hallowed ground would be treated with great respect.
"The (current) soldiers of the army will be thrilled we've potentially found our mates and will be able to say a proper farewell to them," he said.