Fromelles, France (CNN) -- Lawrence Vincent was 21 years old when he joined the Australian Army. The year was 1915 and the world was at war.
He waved goodbye to his 6-year-old brother and was shipped halfway around the world to the fields of France to fight the Germans, arriving the summer after he enlisted.
His war lasted one hour.
Vincent was one of thousands of young men ordered to charge into German machine guns on the night of July 19, 1916, outside this neatly kept French village. The defenders mowed down thousands, killing so many the allies could not recover all their dead.
That's how World War I was fought -- waves of young men charging on foot at enemies who were dug in and waiting with guns at the ready. Millions of soldiers died. The remains of about 165,000 troops from the British Empire alone have never been found, according to experts.
That single night at Fromelles, 5,533 Australians and 1,547 British troops were killed, wounded or left missing in action. More than 90 years after the battle, Fromelles remains the single deadliest 24 hours in the history of the Australian army.
About 1,600 Australian and British bodies were never recovered.
Vincent's body was one of the ones that disappeared. His family was left with nothing but an envelope full of medals to remember him by -- an envelope that lay unopened in Australia for decades after his death.
But this year -- nearly a century later -- Lawrence Vincent's body was identified.
Two years ago, researchers found a series of mass graves near the site of the Fromelles battle. They contained 250 bodies buried by the Germans after the slaughter.
Over the past 15 months, experts have worked painstakingly to identify as many as they can, using uniforms and personal effects, military records, and DNA samples contributed by potential relatives of the dead.
So far, 96 bodies had been positively identified.
On Monday, the 94th anniversary of the battle, a new cemetery was dedicated to be their final resting place.
The last of the 250 bodies -- an unknown soldier -- was laid to rest with military honors in the presence of relatives, dignitaries and their fellow troops.
Britain's Prince Charles and Quentin Bryce, the governor-general of Australia, marched behind the coffin of the last soldier to be interred at the cemetery, called Pheasant Wood.
"We dedicate this cemetery in grateful memory of all those in the land forces in the Commonwealth who died in the cause of freedom," Charles said, referring to the association of nations that used to be part of the British Empire.
"Particularly those who fought and died during the battle of Fromelles and the 250 soldiers whom we remember especially today," Charles said. "May we ever be mindful of them and their comrades in arms of all services and be guided by their example of loyalty, service and selflessness."
Efforts to identify the remaining bodies will continue at least until 2014, according to the Commonwealth War Graves Commission, the non-profit group that is leading the project.
The commission commemorates the dead of both world wars from the Commonwealth. Founded in 1917, it maintains graves and memorials at 23,000 sites around the world.
The Fromelles cemetery is its first new graveyard in nearly 50 years, spokesman Peter Francis said.
The Rev. Mitchell Collins came from Scotland for the dedication, although his grandfather's body was never found.
For him, the event was about "the efforts by people to bring alive, somehow, everybody who died," and taking comfort in knowing that although his grandfather -- also named Mitchell Collins -- never knew his descendants, "you've done something for them."
The body of Lawrence Vincent now lies in a marked grave at the cemetery.
He is known as "Uncle Laurie" to John Vincent, the son of that 6-year-old little brother to whom Lawrence waved farewell in 1915.
The younger Vincent is himself an Australian Army veteran of Vietnam, and he sees a parallel between those who came home from the controversial Vietnam War and those who never came home at all from the First World War.
"They never received the gratitude of the nation that they were entitled to," he said -- until the dedication ceremony on Monday.
"For the family, what it means is we can say, 'Thank you Laurie, on behalf of the family and on behalf of Australia.'"