"De l'ombre a la lumiere" - from the shadow into the light - reads the inscription on the door of the museum at Fromelles, which opens in two months to commemorate one of World War I's fiercest battles.

Almost a century after they fell, the victims of Australia's greatest wartime catastrophe have risen from the anonymity of a mass grave.

Since 2010 their names - or at least those of some of the thousands of casualties - have proudly shone on white headstones in the neighbouring cemetery. Now nextdoor their stories, photographs - even mugs and toothbrushes - will illuminate their lives and commemorate their sacrifice.

Thomas Boucknooghe is the mediateur (guide) at the Musee de la Bataille de Fromelles. He gave Fairfax Media a preview tour, filling in the still-blank shelves and half-finished displays with his vision of what the museum will become. He paused in front of a blank square where a video screen will show some of the thousands of casualties.

"It's really emotional,'' he said. ''You realise how important was this battle. In just 24 hours, how many people died on this battlefield."

There are no plaques on the walls yet, the video screens are silent, and artefacts returned to the battlefield from the Australian War Memorial sit in boxes, acclimatising to the French air.

The tour's arc starts in the shadows of an archaeological dig: explaining the intricate work by many experts that turned scraps of 90-year-old DNA from 250 bodies in the grave at Pheasant Wood into 126 names for the tombstones in the cemetery. The museum will display some of the 6000 artefacts recovered from the land - clothing, badges, even a small toothbrush carved with the name of its owner.

''There were not a lot of personal items on them," Mr Boucknooghe said. "Maybe [the toothbrush was engraved] because they didn't want to lose it or maybe it was just because they wanted to keep the feeling of having something for yourself.''

The ''key point'' of the exhibition is a circular room in which an animated, projected map will show the ebb and flow of the battle, the movement of the troops as the Australians charged through machinegun crossfire to claim German positions that they could not hold as the counter-attack enveloped them.

"They conquered and then they waited … and then the machineguns slaughtered them," Mr Boucknooghe said. Three video screens will detail the 8500 casualties.

"The purpose is not to shock people. It's not a bloodbath we want to show. It's something strong enough to make me feel how impressive was this battle for the survivors."

In 24 hours in July 1916, Australia lost more soldiers than in the Boer, Korean and Vietnam wars together. Many of the dead lay in an unmarked mass grave until a project matched DNA to names and led to the new Fromelles cemetery.

The museum was to have opened on April 23. It will now open at the end of June, about the time possibly the last set of new names are carved into the headstones outside.