The British lost 1,500 men in the battle at Fromelles
Relatives of WWI soldiers from Oxfordshire thought to be buried in a mass grave in France are being asked to donate DNA to help identify them.
The Commonwealth War Graves Commission believes that about 400 British and Australian soldiers are buried in a site near Fromelles.
Ninety one of them were from the Oxford and Bucks Light Infantry. An operation has now begun to excavate the grave.
Investigators need DNA from living relatives to identify the remains.
Anyone who thinks they are related to a British soldier buried at Fromelles has been asked to contact the Joint Casualty and Compassionate Centre at the Ministry of Defence.