On the anniversary of The Battle of the Somme, in which 310,000 soldiers died, a group of Oxford schoolchildren saw for themselves the site of the slaughter

They say that when the wind blows through the arches of the immense memorial at Thiepval it is like hearing the voices of the dead. But this was no such day. The stillness of the summer's afternoon was only broken by the sounds of birds, just as the silence had been on the morning of July 1, 1916, before the whistles blew and the slaughter on the Somme began.

In two weeks heads of state and hundreds of servicemen and women will gather at the French village to mark the 90th anniversary of the five-month battle, which opened with the blackest day in British military history. On that day, the British were to suffer 60,000 casualties, of whom 20,000 died. Little wonder that for many years July 1 was marked by people wearing black arm bands and the drawing of blinds.

The memorial to The Missing of the Somme has now been painstakingly restored in time for the anniversary. Yet on a sunlit mid-June afternoon last week only a small group of Oxford schoolchildren were to be seen in the vastness of the huge columns rising to a huge pinnacle high above the Somme.

They bear the names of 73,000 British and Empire soldiers killed in the battle, which was to drag on until November when only atrocious weather and exhaustion put an end to the savagery. Two columns bear the names of some 500 men of the Oxford and Buckinghamshire Light Infantry who perished. Another shows the names of soldiers of the Oxfordshire Hussars (Queen's Own) who were not to rest in marked graves.

Among the names is that of Capt Arthur Hales, a teacher at Radley, one of those who fell at Thiepval while attacking the German fortress known as Leipzig Redoubt. Hales, earlier awarded the Military Cross for gallantry at Spanbrock Molen, had only taken command of the attack because the HQ had received a direct hit and the colonel had been killed. On the Somme, artillery tore up bodies and corpses and, like those of so many killed in action, his body was never found.

You find yourself desperately wishing Capt Hales might just be among the hundreds lying in the monument's shadow, in immaculately kept graves, with the words Known To God carved on the white stone. Beside them are an equal number of wooden crosses, a most telling reminder that thousands of Frenchmen died here too.

The group of 24 boys gathered together to lay a wreath before 13-year-old George Bland began a familiar prayer in a deep and confident voice: "They shall grow not old, as we that are left grow old . . ." Among the honoured was a Cotswolds boy only a year older than him.

A French woman in her fifties was sufficiently moved to seek out their teacher, Chris Sparrow. "This is how all children should be taught," she told him, clutching his arm for emphasis.

As a teacher who has taken literally thousands of schoolchildren to visit battlefields and military cemeteries, it was not surprising to see him nod his head in agreement. But this visit to the Somme with boys from Summer Fields School in North Oxford, plus one from Matthew Arnold in Cumnor, was always going to be a special one for him and his young charges.

Recently, Chris's book, No Time To Spare, was published, telling the stories of the the 301 former pupils and staff from Summer Fields killed in action in conflicts from the Zulu Wars to the present day. But the Somme took the heaviest toll, inevitably producing heroes among heroes.

The youngsters would later visit the tomb of perhaps the greatest of them all, Billy Congreve, the first British officer to win all three medals for bravery (the Victoria Cross, the Distinguished Service Order and the Military Cross) and one of only three men to have followed their father in winning a VC. His Victoria Cross was awarded posthumously, unusually for continuous bravery over an extended period at the Somme, where he commanded offensive operations of the 76th Brigade.

Many other Oxfordshire schools and colleges will also be remembering deeds of extraordinary courage at the Somme. One of the casualties of the first terrible day was Edward Cook, the former head boy of Abingdon School, which lost nine former pupils on the Somme. Like many others, Edward, who had joined Pembroke College, Oxford, was to linger more than a week before dying from his wounds.

To understand what happened on that single day, let alone over the following blood-soaked weeks and months, requires a guide such as Mr Sparrow, who has visited the Somme more than 30 times, often with his colleague Dominic Price, a talented photographer. For the battle, into which was thrown the entire British effort on the Western Front in 1916, was, in many respects, a series of partial actions, becoming daily bloody struggles for small woods and even smaller villages.

And to comprehend the terrible waste of life you need to travel on the straight Roman road from Albert to the village of Bapaume, an objective less than ten miles from the starting point not reached on the first day, nor after five months of renewed assaults.

It was on this front that the advance began, after weeks of concerted artillery fire on the German lines. It takes a mere three or four minutes in a car from where the great push was launched to reach the furthest point that the advance was to reach. For this there were to be a million casualties in an area just seven miles square, with the blood cost of 600,000 Britons.

Looking over the countryside, the words of the man put in charge of the main thrust come to mind. Making a personal reconnaissance of the prospective battlefield, Sir Henry Rawlinson had told the king's assistant secretary: "It is large, open country with any number of partridges which we are not allowed to shoot. It is a great improvement on the flat, muddy plains of Flanders. It is capital country in which to undertake an offensive when we get a sufficiency of artillery for the observation is excellent and we ought to be able to avoid heavy losses which infantry have suffered on previous occasions."

The weather that summer had been gorgeous. Harold Macmillan, who would go on to become Prime Minister and Chancellor of Oxford University, in a letter to his mother observed that it was "not weather for killing people".

But by then, the landscape, torn apart by shelling, had changed beyond recognition. So had Macmillan. He was injured on July 18 when a grenade exploded in his face.

"The pair of spectacles which I was wearing must have been blown off by the force of the explosion for I never saw them again," he wrote home. On asking his corporal what had happened, Macmillan was told: "Well sir, I saw the German trying to run away. So I 'it 'im and 'is 'elmet came off. Then I 'it 'im and the back of 'is ead came off."

The most northerly sector of the main attack was at Beaumont Hamel, a village at the head of a little valley. (Here it was to take four months to achieve what had been the first day's objective.) Today, it is one of the most impressive memorials, with visitors welcomed by Canadian guides, anxious to impart the story of the Royal Newfoundland Regiment, which saw its first action here. The attack at Beaumont Hamel against German machine guns lasted less than half an hour. Of the 752 men who advanced over that ground, only 68 emerged unscathed. It is now a memorial park, still criss-crossed with trenches, of which there are now surprisingly few on the Somme.

Thankfully, the massive Lochnagar crater remains preserved as a memorial to what happened on July 1. The huge 60,000 lbs mine that caused it had been ignited in a tunnel dug beneath the German trenches at the beginning of the battle.

More than 300,000 visitors a year find their way to the vast crater over 300ft across, 90ft deep, one sixth of a mile round and still today, the largest crater ever made by man in anger.

A large cross of medieval wood from Northumberland was erected on its edge. Each year, on the anniversary of the beginning of the Battle of the Somme, a Remembrance ceremony is attended by up to 1,500 people.

It is certainly a place to stand and feel close to the men who, when the whistle blew, rose from their battered trenches and walked with 66lbs of equipment towards as many as a hundred German machine guns, protected from the bombardment in armoured emplacements. Yet so are the fields we crossed to reach the famous crater.

A walk across the farmland 90 years on will still deliver a rich booty of weapons and ammunition. For my own 15-year-old son, Robert, nothing could have made the history of the area feel closer. The fields of the Somme remain littered with bullets, the once deadly balls of shrapnel, buckles and shells and he was able to see two mud-coated 'live' hand grenades.

One of the biggest shocks for me came on entering the Mametz Wood, upon whose strong defences the Welshman of the 38th division threw themselves and fought a bloody hand-to-hand battle with the Germans. Here in the eerie dense woodland, pocketed with trenches and shell holes, I stumbled upon a large shell completely intact.

But then, during the course of the battle, the British and German armies fired 30m shells at each other, with about a third not exploding. On that first morning nearly a quarter of a million shells fired on the German positions in just over an hour, an average of 3,500 a minute. It was said the barrage could be heard as far as Hampstead Heath.

Mametz was to see acts of astonishing heroism by Capt Noel Godfrey Chavasse, a medical officer, who was to be the only man to win the Victoria Cross twice during the Great War. Chavasse was the second of two identical twin boys born to the Rev Francis James Chavasse and Edith Jane Chavasse at 36 New Inn Hall Street, Oxford. He studied at Trinity College and in 1909 joined University's Officer Training Corps Medical Unit. His regiment was ordered to attack Guillemont on August 7, where of the 620 who took part in the offensive, 106 were killed and 174 wounded, including Chavasse who was hit by shell splinters while rescuing men in no-man's land. It is said he got as close as 25 yards from the German line, where he found three men and continued throughout the night under a constant rain of sniper bullets and bombing.

He performed similar heroics in the offensive at Passchendaele to become the most highly decorated serviceman in the war. Although operated upon, he was to die of his wounds in 1917.

One great Oxford figure who was to survive the Somme was J.R.R Tolkien. His rescuer was to be "pyrexia of unknown origin", as his medical officer called it, better known as trench fever carried by lice.

Tolkien was sent home, where he was to receive a letter from his friend G.B. Smith. Shortly before meeting his death when gas-gangrene set into a shell wound, Smith had written: "May God bless you, my dear John Ronald, and may you say the things I have tried to say long after I am not there to say them," he concluded. To Tolkien's biographer, Humphrey Carpenter, this amounted to a clear call to Tolkien to begin the great work that he had been meditating for some time.

It was tempting to wonder whether their journey to the Somme might in some way or another inspire some of the boys who gathered at the memorial in their later lives. Who knows? But my guess is that the visit to Thiepval made better people of all of them.

No Time to Spare? by Chris Sparrow is published by Gresham Books at £25.