In the countryside around Ypres in Belgium, the evidence of war is in little details it would be easy to miss. It is countryside that isn't quite right, that retains lingering clues of what happened here some 90 years ago.
During the years of fighting around Ypres, the town was nearly destroyed and 500,000 people - soldiers and civilians - were killed.
British troops at Ypres in 1917.
This was the churning middle of the front line of the First World War and it paid the price. In July 1917, in an attempt to break through, the British Army began what was supposed to be an advance from Ypres to Ostend and Zeebrugge.
The plan was to drive the Germans away from the ports, but there were two adversaries in this third battle of Ypres: the Germans and the rain. The armies became bogged down in the wet and the operation foundered in an ocean of horrific liquid mud.
During the height of the war, there was only one direction for escape--underground. During the height of the fighting, the British built massive subterranean structures and tens of thousands of men lived in them.
It is a well documented fact that in 1917 and 1918 more people lived underground in the Ypres area than live in the town today.
Just last year it was revealed that the location of one of these wartime underground headquarters had been tracked down by a team of historians and archaeologists using trench maps and radar equipment.
Now the same team has at last uncovered the entrance to the structure at the bottom of a 40ft shaft and is preparing to open it once again.
The underground centre was called Vampire Dugout (after the soldiers who resupplied the front lines at night) and would have served as a brigade headquarters housing an officer and around 50 men. The structure consists of of a succession of corridors, mess rooms and sleeping quarters connected by corridors measuring 6ft 6in high by 4ft wide.
Vampire Dugout was constructed by the 171 Tunnelling Company of the Royal Engineers, but much of the hard work, the lifting and carrying, was done by the 9th Battalion of the Highland Light Infantry.
At the end of the war the tunnels were abandoned and water soon reclaimed the space. For achaeologists, this is, of course, a good thing. Water means no light or oxygen so it is hoped the contents of the dugout will be almost perfectly preserved when they are recovered.
There is already evidence of this in the shaft that leads to the entrance to Vampire: the wood that lines the walls is in excellent condition
"This takes battlefield archaeology on to a completely new plane," historian Peter Barton told the Herald newspaper. "The preservation of this place is absolutely exquisite."
His team, he said, had been down to the bottom of the shaft and found artifacts left behind by the soldiers, including a shovel. "That was the weapon of the First World War," said Barton. "As soon as you're bogged down you put your rifle down and pick your shovel up and you dig for your life. That's what they were doing here."
The next stage of the archaeological operation at Vampire will be to pump out the millions of gallons of water that have gathered over the years.