Tyne Cot cemetery, Belgium. Photo / Getty
Nothing can quite prepare you for the sight of 12,000 immaculate, upright white headstones, set in regimented lines, glinting in the spring sunshine.
This is Tyne Cot, the world's largest Commonwealth war cemetery. It is immaculate, tended daily by staff and volunteers from the War Graves Commission (CWGC), who have documented as best they can those interred and remembered here.
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The powerful memorial – one of too many in Flanders – is surrounded by white stone walls that bear the names of a further 33,783 British soldiers and 1176 New Zealanders whose bodies were never recovered from the cloying, suffocating mud where they fell.
In May 1922, as the cemetery neared completion, George V, who had made a pilgrimage here, said: "I have many times asked myself whether there can be more potent advocates of peace upon Earth through the years to come, than this massed multitude of silent witnesses to the desolation of war."
More moving still is a quote on another wall, from the unnamed fiancee of a Scottish soldier, John Low, in January, 1918. It read: "The thought that Jock died for his country is no comfort to me. His memory is all I have left to love."
You don't need to look far for touches of humanity. There are headstones and register entries that show many very young soldiers, not out of their teens, perished; perhaps they had signed up with Pals' regiments and were eager to find adventure, little knowing they would soon be commanded to climb out of a trench and walk towards barbed-wire fences, machineguns, mines, gas – and senseless death.
Or, in the museum, photos of wives and children, and letters from home, hoping the promises of it "all being over by Christmas 1914" would come true.
Tyne Cot grew from its original purpose as a repository for those killed in the First Battle of Ypres. Many died on operating tables, or were deemed too far gone for medical intervention at the field dressing station that stood here.
My wife and I were on a private day tour with Nathan, of Flanders Fields Battlefield Tours. No one uttered a word while we were at Tyne Cot, not until we were back on the road. It was part awe and respect and part reflection on the slaughter of barely lived lives.
Our tour began at Langemark, the largest German World War I cemetery. Some 44,061 souls rest there, killed in the series of battles around Ypres. Unlike at Tyne Cot, hardly anyone visits here, least of all Germans.
We learned how, expecting a facile victory that would drive the French and British to the coast and beyond, the German attack included a significant number of students, with just basic military training. Many marched into battle in a state of near euphoria, only to be cut down for the gain of very few yards. More than 2000 of them are buried at Langemark.
Rows of black gravestones lie flat. The Belgians imposed tough restrictions on Germany's dead; the stones were not allowed to stand upright. There were hundreds of burial sites for German soldiers after 1918 but, in the 1950s, Belgium ordered that the bodies be regrouped in no more than four sites.
Germany lost nearly two million men in World War I, the largest number of casualties suffered by any nation. Yet for decades, this chapter of history was hardly taught in German schools.
Today, the care of German memorials in western Flanders, is done by a voluntary association, the German War Graves Commission, and its grounds tended by students.
Dotted around the wider area are small cemeteries dedicated to different nationalities. The Canadian one on the site where the first German chlorine gas attack was launched has an impressive soldier figure standing atop a tall marble plinth.
And there is the New Zealand Memorial on Messines Ridge British Cemetery, which bears the names of 839 New Zealand soldiers who died in the Battle of Messines in 1917 and have no known grave. The cemetery also contains the graves of 115 New Zealanders.
We moved on to the brilliant two-level museum at Passchendaele, a name synonymous with Ypres' third battle, which ended in a muddy stalemate. There you can see uniforms, artillery and ordnance - as well as walk-in replica trenches and dugouts.
You can also get a replica whiff of chlorine gas, as well as others used to deadly effect later – mustard gas and phosgene. You inhale just enough to make you feel nauseous – and reflect that although terrifying, it would have been merely one further hell for troops to endure, if it did not kill them.
We had lunch in the pretty town of Ypres, which is something of a phoenix-like wonder, given that barely a stick was left standing there after 1915. The central Wool Hall has been restored (the World War II bullet holes are real) and houses the brilliantly fascinating In Flanders Fields Museum and research centre.
An electronic poppy-shaped bracelet unlocks fascinating holographic video displays, often involving actors in uniform or as civilians, telling their Great War experiences, the hardships at the front and atrocities visited on ordinary Belgians.
At Ypres' Menin Gate, the poignant Last Post ceremony has been repeated every evening at 8pm since 1928.
The night we visit, schoolchildren are among hundreds at the imposing gate as three men from a fire brigade band perform the duty.
A British schoolgirl then stands in the centre of the giant stone arch fronted by carved lions and recites the lament:
"They shall grow not old, as we that are left grow old: Age shall not weary them, nor the years condemn. At the going down of the sun and in the morning, We will remember them."
It wraps up an unforgettable few minutes shared with many nationalities, old soldiers, civilians and students alike – the latter giving you hope that Europe will never again descend into the hell that visited Flanders.
Princess Diana stayed there, and now so have I.