SO, at the going down of the sun, we remember them. But then night falls. The last warrior who fought in 1914-18 is dead. No longer there to wear a poppy, to stand at the Cenotaph in central London on Sunday; no longer able to provide a link to the conflict that we thoughtlessly call the great war, the one that was really the Great Carnage: nearly 900,000 young Britons killed in the trenches, nearly 1.4 million French and over two million Germans lying close by, shot, bayoneted, blown to smithereens.

Add in, of course, the Austrians, the Turks, the Romanians, Americans, Australians, Indians and so many, many more. Never forget the inevitable millions of Russians, the Serbs, the Bulgarians, the Italians. The numbers are so huge, so monstrous, that they cannot be clinically calculated.

Ten million men and women in uniform slaughtered? Five million or more civilians caught up in the struggle? How do you count the millions who died of disease and famine — or even begin to guess at the wounded and maimed? How do we truly remember them now?

There are letters home from grandfathers or great grandfathers lying in cupboards, perhaps. There are tales passed down over generations. There are memorials on village greens. And there are heartbreaking poems, plays, films, histories; the life of art after death. But the witness I still remember best, from half a century ago, came in person from a straight-backed Liverpool businessman in an immaculate grey suit.

“A short while ago,” Arthur Behrend wrote in Make Me A Soldier, his diary of the Gallipoli disaster, “I took my typescript from the parcel in which it had lain undisturbed for over 40 years ... I had changed so utterly that I could not believe I had written one word of it, let alone taken part in the events it described. It was as though I was reading some bygone campaigner’s account of the Crimea, even of Waterloo....”

Behrend’s Gallipoli diary, just like As From Kemmel Hill, his account of Flanders’ fields, is unique because it’s eloquent, intelligent but also doggedly loyal. It doesn’t say that he and his men were lions led by donkeys. Though they were. It doesn’t brood on the cruel imbecility of war. Though it could have.

It just tells us what the great war was like: mud, failure, courage, blood by the river full. It echoes, more poignantly than I’d have thought possible, what our returning heroes say about the hell of Helmand. Not that this was some crazy mission: just that it was a job that had to be done.

Afghanistan isn’t the war to end war. Afghanistan is war on a continuing basis. We might have learnt from failed wars on terror, on drugs ... but we haven’t. We still dispatch young men and women to their deaths by the thousand. Pragmatist, not pacifist, we brush away the lessons of 1914-18. At the going down of the sun, we will remember? Perhaps.

Yet then night falls: and, all too easily, we forget.— The Guardian, London