SIEGFRIED SASSOON was the only First World War poet to name Passchendaele. In his poem Memorial Tablet, he imagines a soldier commemorated on the tablet speaking: “Squire nagged and bullied till I went to fight/… I died in hell – they called it Passchendaele.”

The poem even immortalises the battlefield’s infamous mud, which probably claimed as many lives as the shells and bullets: “My wound was slight, / And I was hobbling back when a shell/ Burst slick upon the duck-boards: so I fell/ Into the bottomless mud, and lost the light.”

Sassoon hated the Menin Gate, unveiled ten years after the battle. He pictured “the Dead” struggling from “the slime”, to “rise and deride this sepulchre of crime”. He viewed the long engraved lists of the missing 55,000 as “these intolerably nameless names”.

In fact relatives who today seek out a name feel great comfort on finding it. And the nightly sounding the Last Post at the Menin Gate, a ceremony which, though long formalised, began as a lone tribute by a local policeman, is arguably the most moving act of remembrance.

This week, the centenary of the start of the three-month battle has received all the high-profile attention that the presence of Royalty can bestow. The Duke and Duchess of Cambridge were deeply moved at the Menin Gate, where the King of Belgium paid tribute to the “immense sacrifice” of the dead and expressed his pride in the local community’s maintenance of the Last Post tradition. At the nearby Tyne Cot cemetery, the Prince of Wales promised “we will never forget”.

Slotted into many of the reports has been the contemporary description of the First World War as “the war to end all wars” – the Passchendaele mud a potent reason. But our world was at war again just over two decades later. And since then conflicts have never ceased.

No war is exactly like the last. The First World War, though fought largely with the same weapons as the Second, was the last in which the victims were chiefly members of the opposing armies. The second was the first in which civilian deaths figured as much, if not more, than military. The two atomic bombs that virtually ended it confirmed the changed balance.

Where are we heading now? The world was probably at its safest the day the second world war ended. Certainly it looks no safer now than at the height of the cold war. Cyber warfare, the latest example of our demonic propensity to apply inventions to war, is being conducted at this minute. Major nations spy on each other by means ranging from satellites to submarines.

As another poet, Gerard Manley Hopkins, put it, “a pure peace” does not allow “alarms of war, the death of it”. Does anyone reading this believe we have seen the last of war? That the frictions every day testing our impure peace will not one day somehow coalesce into catastrophe?

What has this to do with Passchendaele? That when we say “never again” it would be fine if we were looking back from a more enlightened time – which has banished war. But we’re not. And when the next war arrives, the hell will extend far beyond muddy battlefields like Passchendaele, or even cities like Hiroshima.