Sunset on the Somme and a sepia mist shrouds the Serre road like mustard gas. The scattered trees stand like silent, frozen explosions and but for the bark of distant shotguns, all is quiet on the western front.

The landmarks of butchery are scattered along a 15-mile strip from Gommecourt in the north to Maricourt in the south, like the attractions in Death’s own theme park.

There’s Luke Copse, where the Accrington Pals were wiped out. Over the road is Hawthorn Ridge, where 19,000lb of ammonal was detonated beneath a German redoubt; and a short stroll away is Newfoundland Park, a delightful-sounding spot where hundreds fell under fire from just five German machineguns.

I’ve come to France’s killing fields in search of two men, and I’m already halfway successful. Sergeant Frederick George Chesterman is my children’s great-great-grandfather. Little is known about his death, except that it was violent, painful and it came out of the blue on August 23, 1918. He now lies with 601 others - many known only unto God - in the military cemetery at Foncquevillers.

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• In search of my uncle's grave on The Somme

Nobody has visited him before, so I’m planting a rose of Picardy to atone for 90 years of neglect. The soil of the Somme is soft and easily worked - good for soldiers and gravediggers - and as I heel in the roots, I can’t think of much to say. The platitudes are hollow, and disingenuous: well done, Fred. You didn’t die in vain.

The other I seek knew that to be a lie. Lieutenant Wilfred Owen - the finest poet of his generation - received his baptism of fire a few miles south of Sgt Chesterman’s grave, and nine decades later I’m standing in the exact spot where Owen first saw through the smoke and mirrors of the glory of war.

Close your eyes and you can still hear the shrill, demented choirs of wailing shells that fell upon the company as they occupied a warren of “old Boche dugouts”, immortalised in the poem The Sentry. A few days later, in the same spot, “pockmarked like a body of foulest disease”, Owen was gassed. It was this event that inspired Dulce et Decorum Est - perhaps the greatest war poem ever written.

After falling into a cellar in the frontline village of Le Quesnoy-en-Santerre, 20 miles to the south, Owen was hospitalised in the Number 13 Casualty Clearing Station in Gailly, a few miles north. No trace of either remains, so I head east to spend the night in Péronne.

By the time he returned to the front, the Manchesters were battling to breach the German defences around Mont St Quentin. It is a charmless land, a jumble of housing and industrial estates beside a busy rural road that belies the horrors of nearby Savy Wood. It was here, in this spindly thicket, after surviving a barrage he described as “a tornado of shells” and 28 hours in a hole with the dismembered body of a brother officer, that Owen’s nerves snapped.

The doctors declared him “unfit to command” and on June 13, 1917, he returned to Blighty for a long stay at the Craiglockhart War Hospital, on the outskirts of Edinburgh. It was here that he met the celebrated antiwar poet Siegfried Sassoon and formed a relationship that produced such incandescent works of genius as Anthem for Doomed Youth, Disabled, and Exposure, and marked the emergence of a talent that would burn as brilliantly - and as briefly - as the magnesium flares that lit up the front.

Driven as much by shame as by a desire to emulate Sassoon’s swashbuckling style, Owen returned to France in September 1918, and I pick up his trail in the ramshackle village of Corbie, outside Péronne. The temple-like boneyards of the Somme, with their marbled cloisters and Lutyens-designed memorials, are far to the west, replaced in this rarely visited region by pocket-sized cemeteries, scattered like lost handkerchiefs. Look hard and you’ll find a couple of hundred buried behind a barn, three dozen beside an overgrown churchyard, and 96 laid out at the corner of some foreign field that is forever England.

It was in Corbie, as the gravediggers rinsed the helmets of the dead for reissue, that Owen wrote Spring Offensive - to me the most pitiful, lyrical and terrifying account of warfare ever written.

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