Two British First World War soldiers whose graves were wrongly marked in a Somme cemetery for more than a century are to be laid to rest with full military honours.
Privates William Marmon, 21, and Harry Carter, 20, lost their lives along with six other soldiers when a 15-ton German underground mine exploded on November 22, 1915.
Hundreds of tons of earth engulfed the dugout where Ptes Marmon and Carter, of the 10th Battalion the Essex Regiment, were most likely on sentry duty.
Their deaths were marked around the time they perished with named graves and headstones at the Commonwealth War Graves Commission's Albert Communal Cemetery Extension in France.
But, thanks to dogged detective work by experts, it emerged a century later that rather than being recovered and buried, the men had lain underground where they fell in the village of La Boisselle.
A clerical error by the then War Office some 100 years ago is believed to have led to the collective grave being wrongly marked with their names, the archaeological evidence suggests.
On Wednesday, three years after the remains were found, Ptes Marmon, from Holborn, central London, and Carter, from West Ham, south London, will be buried with full military honours.
Nine surviving relatives will attend the service, which will be led by the Revd Richard Priest and organised by the Ministry of Defence's Joint Casualty and Compassionate Centre (JCCC).
At a press conference in Arras ahead of the service, Trevor Newland, 60, from Ilford, north-east London - Pte Marmon's great-nephew, said: "I'd never heard of him even though I knew his sister, and she never said anything about him."
Brian Churchyard, the great-nephew of Pte Carter, said: "We've got some letters from Harry from when he was stationed before he went to France.
"Reading through them is really poignant, particularly the ones he sent to his mum and dad. He always signed them, 'your loving sons Harry and Charlie'.
"And there was one where he said, 'I've got a bit of skirt'. He was an East End lad."
Peter Francis, of the CWGC, said he had never before seen such level of detail about two fallen soldiers before.
The discovery came in 2013 after a professional archaeology group, the La Boisselle Study Group (LBSG), formed by Briton Peter Barton, excavated trenches in an area known as the "Glory Hole".
Beneath the two-hectare site, which included British, French and German trenches, a field of mine craters and remnants of a farm, was a labyrinth of wartime tunnels.
In the trench outside the post, the remains of the two fully-kitted men were found beside their rifles and ammunition, grenades and flares.
Little figurines of children were also found in a pouch, along with a bullet carved into a love heart, the press conference was told.
A file of evidence was sent to the JCCC who used genealogy research to identify and trace the surviving relatives of all eight soldiers reported as being killed.
DNA analysis proved the remains found at the explosion site were Ptes Marmon and Carter. The inscriptions on the existing grave headstone have now been amended.
On average, up to 40 soldiers every year are discovered on the former Western Front battlefields. French law dictates that the CWGC be involved when a body is found.