Perhaps we need censorship. The Isis vandals now destroying the greatest sites in ancient Mesopotamia have no care for history, so why do they bother? The answer is to get publicity. As with beheadings, they want to taunt us with their outrages. So why give them what they want, which is our obvious dismay? Why encourage more destruction?

To read of the loss of ancient monuments is heartbreaking. When they date from the dawn of western civilisation in the Mesopotamian valley, the pain is the greater. Nimrud, Hatra and Nineveh are 6,000-year-old bedrocks of our culture. Like the smashed statues in Mosul museum, their destruction tears at the roots of Eurasia’s shared identity. That identity may stay recorded in books, pictures, museums. But the continuity of place is lost. The narrative is snapped.

Many will say, so what? In peace and war, we are constantly told that people should take precedence over things. I have spent my life trying to save beautiful buildings, streets, towns, woods and fields from those who, usually with a profit in mind, claim that ‘people are more important’. They are, and they are not.

I am sure we could save lives by not conserving the past and spending money elsewhere. The bomb, the crudest weapon of war, always justifies its devastation as ‘saving lives’. So does torture. But a sign of civilised people is that they balance the short-term interest of one generation against the values enshrined in the past, and against the right of future generations to share that past. Since the dawn of time, confident communities have treasured their history. That is why Isis leaves us horrified.

Of course blame lies with the perpetrators of horror. But this madness was unleashed a decade ago by those harbingers of anarchy, George Bush and Tony Blair. They destroyed order in Iraq. To dismantle the framework of control in any state, however cruel, is to let the angels of hell run riot. I witnessed what coalition forces allowed to happen after the invasion of Baghdad in 2003, the looting, the digging up of sites, the black market in antiquities. I saw the denial of guards for Baghdad museum. It was like throwing open the doors of the National Gallery in London for people to take what they wanted.

At least in the second world war — the most destructive in history — western armies carried with them lists of reserved sites and no-go areas, and tried (as in George Clooney’s The Monuments Men) to rescue looted treasures. They tried to avoid bombing ancient cities or shelling Arezzo. In Iraq bombs fell on historic buildings. Tanks crashed through ancient sites. Babylon and Ur became military bases. Yes, Isis is awful. But we started this one.

When I protested the dropping of high-explosive bombs near ancient Serbian churches during the Kosovo war of 1999, I was told it was unreasonable to expect the RAF to be pinpoint accurate in its targeting. The heirs of Bomber Harris are not squeamish about the far end of a bomb site, be it a human being or a historic building. There will always be ‘collateral damage’. On this 70th anniversary of the Dresden firestorm at least we say sorry. We did not do so at the time. We saw eliminating an enemy’s heritage and culture as justifiable revenge — as Harris’s apologists still do. That is roughly the Isis approach.

There is no point in the United Nations secretary-general, Ban Ki-Moon, declaring the destruction of Nimrud ‘a war crime’, or Unesco declaring it ‘a direct attack against the history of Islamic Arab cities’. There is in place a clear 1954 Hague convention protecting ‘cultural property in the event of armed conflict’. It remains unratified by two states, America and Britain, ‘for reasons of national security’. That is two states, plus the Taleban and Isis. As Robert Bevan has written in The Destruction of Memory (2006), the razing of history has long been the most hypocritical weapon of war.

Nor are we getting any better. In 2001 the Afghan Taleban destroyed the Bamiyan Buddhas. Since then Unesco has spent 12 years feuding over whether and how to restore them. Nothing has been done, such that some want to leave the ruins as a ghastly but ‘authentic’ memorial to the Taleban. That is precisely what the Taleban wanted. World cultural bureaucracy is at the service of fanaticism.

What the West can and should do is prepare for the aftermath of this devastation. A huge task will one day face those who care for these places. Syria and Iraq host the records of the dawn of the known world. The ancient city of Aleppo has been flattened. The Assyrian and Parthian capitals are bulldozed. The oldest Christian churches on earth are being wiped off the map as you read this.

These sites must be restored, with replicas if necessary. There should be no ideological Unesco nonsense about ‘inauthenticity’. As many of Europe’s medieval churches are Victorian, so many Mesopotamian sites had been heavily restored. Like Arthur Evans at Knossos, early archaeologists were keen to ‘stabilise’ these sites, including Agatha Christie’s husband, Max Mallowan, who worked at Nimrud. The Bamiyan Buddhas were themselves partly restored. The ruins of Palmyra were reconstructed by the French. As for what remains of Babylon, it is mostly the creation of a certain Saddam Hussein.

The Germans reacted to the RAF’s destruction of Hanseatic Lubeck by rebuilding it facsimile (and retaliating with ‘Baedeker’ raids on Britain). Lubeck is now a world heritage site. We did not rebuild Coventry or Bristol after the blitz, largely because modernist architects said it would be unsocialist. That is why tourists prefer Bath and York.

In Iraq and Syria we have the records, the scholarship, the skills and the money to reinstate these sites and re-fire our imagination. We played a part in their destruction. Our duty is to do what we can to rectify it. Of course replacements are never the same as originals. But are defiance in the face of fanaticism. They are far, far better than nothing.