When John Key visits the Somme battlefield tomorrow to honour the fallen of World War I, he will see a place that today cannot be further from its description as "the mouth of hell".

In 1916 in France, there was no place on Earth worse than this corner of Picardy, churned by industrialised warfare into a moonscape of mud, blood, bones and barbed wire.

The mutilated forests have regrown and tractors trundle across the fields to sow and reap the grain. A white scar left in chalky soil by collapsed trenches and an annual harvest of shells brought up by the plough are among the few signs that this is a site where more than a million men were killed or wounded.

The vivid reminder of the human cost lies in the war cemeteries, with their emerald lawns and pristine white crosses. And behind each carved name lies a story.

Many deaths date to September 15, 1916, when the New Zealand Division entered battle, supported by tanks for the first time in warfare.

And two of the names converge: H.R. Wilton and S.T. Wilton, both of B Company, 4th Battalion, New Zealand Rifle Brigade. They had sequential serial numbers, 26/423 and 26/424, for they joined up on the same day.

Hughie and Sidney Wilton were farm lads who signed up in August 1914 as war mania swept New Zealand. They died on the same day, little more than two years later on the same battlefield, possibly within yards of each other, although this will never be known.

Hughie, 27, buried in Flers, was killed in action, while Sidney, 29, was listed as missing - a euphemism for a body blown to smithereens - and his name features on the Caterpillar Valley Memorial where Mr Key will pay his respects.

Photos show Hughie as a stocky young man in the rough khaki of a rifleman, a face betraying the quest for a bit of adventure and glory, yet also the bluff look of life on the farm.

Their parents, Thomas and Annie, wed in 1882, forging a successful marriage that did not preclude strong differences of opinion. "Following the wedding, they walked down opposite sides of the street," says a history of the Wiltons, to whom I am related through my mother.

A photo shows Annie wearing a prized, if battered, "Sunday best" frock, her hair pulled back resolutely, her eyes large as if looking to the horizon for the next challenge.

These were not hard to find in the rural life of early New Zealand.

Thomas headed to the Australian goldfields to seek a fortune while his pregnant wife and two young children eked out a life.

When Annie gave birth, she had to send their boy Fred - aged only 4 - to run to get the midwife, 5km away, at 3am.

Unsuccessful in the gold rush, Thomas was able to return only after Annie scraped together his fare home. All he had was a tiny nugget, which he gave to Annie and she kept all her life.

With toil, the family made headway. Thomas bought a small farm, named Kiora, at Rangitumau Valley where they raised 50 sheep. By 1914, they had 240 sheep and enough to buy them a bigger spread at Pahiatua. Their children, now grown up, could devote their time to the business.

But just as things were looking up, war broke out and New Zealand sent its men to the other side of the world.

In a letter from France after arriving by troopship, Sidney spoke with awe of the railways - "some of the engines seem big enough to sink New Zealand" - and cast an eye over French farming, deeming it primitive given the country's lush potential.

"Hugh is writing to Isla [his wife]. He wants you to think this is half his," said the letter. "He is in bed at present, we sleep alongside one other, he got the papers dad sent and please send some more, they are appreciated very much."

In September, the New Zealanders were thrown into the maw. An artillery barrage was laid down as the British unleashed their secret weapon, the tank.

The behemoths crawled towards the German lines, spreading panic that enabled the Kiwis to advance towards Flers. But it was not the great breakthrough the allies craved - too many of the machines broke down.

After losing two sons on the same day, Annie had still not had all her dose of misery. In November 1917, Thomas died of pneumonia, aged 60. A third son died in a road accident.

With little else other than her sons' war medals, Annie picked up the pieces. Helped by three surviving sons and her daughter, she made a success of the farm. For all her tragedies - "setbacks" as they called such events in hardier times - she had a long life and a happy one.

Annie died in 1954 at the age of 95, having lived in Pahiatua for 40 years.

Her obituary in the Wairarapa Times-Age praised her unfailing humour, her roots to the early days of the community and her popularity: "A supporter of any deserving cause."