On a small hillside above the Somme I once found an ancient oak tree with a series of metal spikes driven into the trunk. In the First World War, a local resident told me, soldiers had used the tree as a lookout post across the trenches, and the spikes formed a rudimentary set of steps. About 15 feet from the ground, someone had carved the initials “AP”.

I found myself wondering if AP had survived the carnage of the Somme. Over the decades the tree had grown around the metal spikes until just the tips were visible: a physical memento of war, grown into the landscape. I have visited hundreds of war graves on the First World War battlefields, but none that has remained in my memory like the old tree carrying the shrapnel of war in its body.

The most moving wartime monuments are often the informal remnants, the decaying detritus, the small relics and souvenirs left behind by ordinary people after the tide of conflict recedes: the graffiti scrawled in a bomb shelter, or initials, names or messages carved on a tree. Perhaps because they face death, soldiers are often determined to leave some souvenir of where they have been. On a larger scale, one can still see the brick bunkers on the South Coast, and the remains of the Mulberry harbours built for the Allied invasion of Normandy and still visible more than six decades later.

Formal war memorials commemorate one face of war: the lines of graves carefully tended by the Commonwealth War Graves Commission, the plaques on the walls of Paris commemorating where heroes of resistance fell, the names inscribed on granite in every British town and village.

Organisations such as the Imperial War Museum and the Cabinet War Rooms do a superb job of preserving the wartime past. Auschwitz and the village of Oradour-sur-Glane in central France, preserved as it was on the day that the Nazis burnt it and murdered its inhabitants, stand as monuments to a horror that should never be forgotten.

But beneath this is another layer of relics that will slowly disappear. French sappers still collect unexploded shells and other munitions from the First World War battlefields, but in steadily decreasing numbers. One day the tree above the Somme with the spikes in it will die.

It is impossible to preserve every relic of war, but to cut down and pulp 150 living monuments because they were deemed dangerous is a small but telling act of historical vandalism. Like old soldiers, the Name Trees of Normandy and their wartime carvings should have been left to fade away.

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