A flash of white Portland stone by the side of the road; then another and another, glimpsed briefly on the sloping uplands, all but concealed behind a curtain of early-morning mist.

This is the land of the dead and their cities are everywhere.

The Somme, pickled and preserved in calamity, is a dark land, immortalised by the valedictory poetry of doomed youths. But for the war, there is no reason to come to this place, a construct of myth, memory and melancholy imbued with a sense that nothing else has ever happened here, and that now nothing else ever can.

True, as the weak sun rises, burning off the mist and setting ablaze the autumnal colours of the neat cemetery hedges, the farmers of the Somme are busy turning the land. But their tractors, industrious all about in this season of ploughing, must work in perpetuity around and over the dead and the detritus of their dying.

In the surrounding polygonal patchwork of large, chalky fields, where the head may scarce be turned without the eye falling upon another orderly English garden of the dead, Rupert Brooke’s lines spring to mind. In the Somme, where the Commonwealth War Graves Commission cares for 250 cemeteries and six memorials, the corners of so many of these fields are indeed forever England.

They are also potential death traps. At this time of year two crops can be seen heaped by the sides of the fields, awaiting collection – mounds of sugar beet and the so-called “iron harvest” of unexploded munitions.

On a farm track I almost stumble on three unexploded artillery shells, unearthed and left by a farmer for collection by the Département du Déminage (mine clearance), which since 1946 has recovered and destroyed millions of such items. Every year two or three people are killed by unexploded ordnance.

Small wonder that tractor drivers hereabouts sit on armour-plated seats. I leave well alone.

In such a landscape, polluted by gas, lead and iron and populated by ghosts, it is easy to stray into quagmires of melancholia. One needs a guide with feet firmly on the ground.

Few are better suited to the role than Gordon Corrigan, retired major in the Gurkhas, historian, Holts tour leader and author of Mud, Blood and Poppycock, a book that destroys almost every myth of the First World War that we have come to accept as fact. His plan is to focus on the first day of the Somme, which remains the bloodiest day in British military history, and to work our way from north to south along the 14 miles of the British attack.

At 7.30am on July 1, 1916, after a week-long artillery bombardment during which 1.5 million shells fell on the German positions, 120,000 British and Commonwealth soldiers, the taste of the rum ration still on their lips, left their trenches.

The Germans had suffered terribly, but they were well dug in and by nightfall more than 19,000 of Kitchener’s New Army, many of them neighbours or colleagues who had joined “Pals” regiments together, were dead.

By the end of the offensive in November, the Germans had been pushed back seven miles and more than 70 towns and villages (or their rubble, at least) had been retaken at a total cost of 90,000 French, 96,000 British and 150,000 German dead.

Can it possibly have been worth it? Corrigan, whose military training and historian’s eye allow him to see beyond tactical losses to wider strategic gains, argues convincingly that it was. Without the Somme to divert German resources, the French would have bled dry at Verdun, 130 miles to the south, and Germany could have won the war.

He is right, of course – freedom always comes at a price. But look at all these boys lying here.

We are standing at the edge of a lonely field half a mile off the D919, north of Beaumont Hamel and at the extreme left and most costly end of the British attack. Here the 31st Division, composed mainly of “pals” from Yorkshire, died in large numbers.

Behind us is a copse, the ground still scarred with trenches and shell-holes. This is Sheffield Memorial Park. Beyond it, in Railway Hollow cemetery, lie 107 mainly very young men. Within a few hundred yards across the fields are two other cemeteries, Luke Copse and Queens, holding between them a further 383 dead. Thousands more lie near by.

On the Somme, the dead are, quite literally, never out of sight.

Corrigan’s rational soldierly perspective proves fortifying as we work our way south along the British front, for as we go, pausing to view some ridge or sunken road from which this or that battalion rose and walked towards extinction, the dead come with us. As the day wears on and their numbers rise, so, too, does a kind of spiritual nausea in my stomach.

Near the village of Grandcourt we pause at the Regina Trench Cemetery, the site of a German stronghold taken by Canadian troops in October and November, 1916. Many of them lie here now, among the remains of 2,279 Allied troops.

A tractor is ploughing the field adjoining the cemetery and Corrigan spots a relic that I can bring home safely. It’s a lead ball, about the size of a child’s marble, and one of more than 300 blasted from a shrapnel shell 90 years ago.

So why come here? Is it really “lest we forget” the sacrifice of the dead we never knew, who died fighting to preserve a political landscape we no longer recognise – or is our motive less noble, a kind of historical rubber-necking? The Thiepval Visitor Centre says that 200,000 visitors visit the Somme every year, and that more than 80 per cent of them are British.

What do we take from this place, besides a sense of sorrow, a lump of lead and the mud on our boots, rich with that dust “whom England bore, shaped, made aware”? I get an answer of sorts at Mansel Copse, just off the D938 between Fricourt and Maricourt. From here on July 1, two battalions of the Devonshire Regiment rose from their trench to attack the village of Mametz. Three days later the survivors buried 161 of their dead in the same trench and here they remain, beneath two ranks of closely ordered headstones.

Among them is William Hodgson MC, a 23-year-old lieutenant whose last poem, Before Action, ended with the lines: “By all delights that I shall miss, Help me to die, O Lord”. Two days later the Lord obliged, although he left the details to a German machine-gunner.

The small Devonshire cemetery, boxed in and overshadowed by trees, is a family affair and here, more than anywhere that I have visited this day, I feel I am intruding on private grief. Then I read the simple inscription on the small stone memorial by the gate: “The Devonshires held this trench. The Devonshires hold it still.”

The ten words speak volumes across the generations and I find the connection I have been seeking all day. I also find I have tears in my eyes. The shrapnel weighs heavy in my pocket.

As the light fades and the mist steals back across the Somme, we return to our hotel outside Albert, passing the Airbus factory at Méaulte on the way. Here, 1,500 Frenchmen toil to produce the front ends of aircraft, while 370 miles away in Stade a similar number of Germans assemble the tails. It’s hard to know if this hulking symbol of European unity is a vindication of the sacrifice of the dead who surround it or a monument to its futility.

Less than a mile away, in Dartmoor cemetery, are the remains of 768 Commonwealth dead, including father and son George and Robert Lee, a sergeant and a corporal in the same artillery unit who fought together, died together in the same action and now lie together, side by side.

The Lees came from Peckham, southeast London, just a few streets away from my grandfather, who also served on the Somme in the Royal Field Artillery. He survived, to father my mother, which in turn led to me. It is through such shrugs of fate that so many of us are connected to this place.

Back home, I take off my boots by the door, in case the dried mud of the Somme gets into the carpet. I can’t say when I will get round to cleaning them.

1,508,652 Shells fired during artillery bombardment in week before Battle of the Somme
57,000 British and Commonwealth casualties on first day of fighting. Of these, 19,200 were killed
1,200 yards – maximum distance taken on first day of fighting, at the village of Montauban

Need to know

Jonathan Gornall travelled with Holts Tours (0845 3750400, www.holts.co.uk), a battlefields and history specialist that offers 16 First World War tours in 2008.

“Three Armies and Four Years on the Somme” is a four-day tour looking at the British, French and German armies’ experiences of the war on the Somme, and includes the Somme commemorative ceremony on July 1. The cost of £485pp, based on two sharing, includes half board in a three-star hotel and coach travel from London.

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