WHEN my elderly aunt died 15 years ago, it was my task to clear her house. On the top shelf of her wardrobe, I found a large, heavy foolscap envelope. I lifted it down and gingerly emptied it out on the kitchen table. The last few weeks of a man's life spilled across the blue Formica.

My Uncle Arthur died, aged 19, on the first day of the Battle of the Somme - July 1, 1916, the day often described as the most futile in British military history, and my father's sixth birthday.

Arthur was my aunt's - and my father's - eldest brother, but, as far as I knew, the only memento of him was a sepia photograph taken just before he died. He sat on a wooden crate outside a tent in his Royal Engineers uniform and gazed at the camera impassively. He looked little more than a lad.

The envelope's contents filled in his story. Here was a railway ticket ("Return Journey: Third Class") dated May 16, 1916. It took him back to the front line in France after his last week of home leave.

Here was a yellowing cutting from the following day's Sheffield Daily Independent. "Going Back to Duty and Danger" announced the headline over a photograph of half a dozen soldiers. Uncle Arthur was on the left, rifle in hand, still impassive. Seven weeks later, he was dead.

Here was the metal identity disc found on his body; a heavy copper plaque commemorating his death; a scroll of honour, with King George V's crest at the top and Sapper Arthur McClarence's name at the bottom. A letter to my grandmother assured her of "His Majesty's high appreciation of the services rendered" by her son.

And here, mounted on card, was an official 1920s photograph of his gravestone in a military cemetery somewhere in northern France. A shaft of morning sunlight threw the lettering on the simple slab of stone into crisp relief and highlighted a small scar on its right-hand side. The inscription along the bottom - "Gone but not forgotten" - was partly covered by dead leaves.

Behind it, the rows of gravestones of some of the other 20,000 British troops who died on that July day receded until they were out of focus.

My grandmother and then my aunt kept these relics for almost three-quarters of a century, but no one from the family ever went to see the grave. One day, I thought, I must try to find it. Earlier this year, I did. I went with Holts Tours, the pioneer of battlefield tours, now in its 26th year. It takes parties to Waterloo, Agincourt, Vietnam and the Falklands, but the First and Second World Wars account for the bulk of their business.

I joined the "Tipperary tour" to Ypres, Vimy Ridge and the Somme; four full, highly organised days of crossing and recrossing the former battlefields of France and Belgium by coach.

It's a sobering but not sombre trip, with evening discussions exploring such unfashionable issues as duty, comradeship and patriotism after days of looking at trenches, dug-outs, tunnels, memorials and, at practically every turn, military cemeteries. There are 1,000 British cemeteries in France alone, in the corners of fields, across allotments, through housing estates, alongside motorways and railway lines.

For most of the time, they are the only obvious reminder of conflict. It's difficult to relate today's quiet towns, neat villages and rolling farmland to the horrors of the war, when soldiers spent weeks wading through waist-high mud. The grassed-over trenches once alive with men, rats and lice now look almost like corners of landscaped gardens.

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