On the Hungarian border, thousands of migrants press forward against razor wire fences, chanting and screaming as lines of police stand grim-faced against them.

In Croatia, scores of others clamber through the windows of trains to hitch a ride westwards. To the south, boats loaded with people who’ve travelled up through Africa set sail from Libya heading for Italy.

They have all called Europe’s bluff. They have taken seriously the high-minded talk of European values, and now most of them will experience European hypocrisy as doors close once more, EU migration rules crumble and the continent divides.

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Unnoticed by most Europeans, the asylum rules have widened since 2004 so anyone in the world at risk of ‘serious harm… by reasons of indiscriminate violence in situations of international or internal armed conflict’ can claim protection — which in practice means permanent residence — in an EU country

The rich north of Europe is pitted against the poorer east, and liberal-minded, well-educated citizens diverge from the silent majority who still think that charity begins at home, even if it doesn’t end there in a crisis like this one.

How did we get to this crisis point? Unnoticed by most Europeans, the asylum rules have widened since 2004 so anyone in the world at risk of ‘serious harm… by reasons of indiscriminate violence in situations of international or internal armed conflict’ can claim protection — which in practice means permanent residence — in an EU country.

This fine sentiment worked only so long as relatively small numbers of people were able to reach Europe to claim that protection. But when border controls in southern Europe collapsed a few months ago and word got out in the Syrian refugee camps, and among thousands of others in Iraq, Afghanistan, Eritrea and parts of sub-Saharan Africa, the great caravan began to roll.

Riding the wave of sympathy triggered by the photograph of drowned toddler Aylan Kurdi, the German Chancellor Angela Merkel then exacerbated the situation by unilaterally declaring all Syrians would be welcome in Germany, and not returned to their country of first arrival, as EU rules require.

(Though official figures yesterday revealed that in the past four months, just one in five of those seeking asylum across Europe has been Syrian.)

This is the reality in which we have to think about the question of our obligations to suffering humanity. It is not a matter of discrete tens of thousands arriving in Western Europe, as was the case in post-war Britain with Poles, Hungarians, Greek Cypriots, East African Asians and others.

Today, it is potentially tens of millions, when one considers those suffering in the face of conflicts in Syria, Iraq and Afghanistan — not to mention the 40 per cent in poor countries who want to move to rich ones, according to a Gallup poll.

And so many more can now move thanks to the legal and physical permeability of Europe’s borders, as well as the communications and transport infrastructures that give them both windows into our societies and the means to get here.

To some on the Left, this is a cause for celebration. For the new Labour leader Jeremy Corbyn, and the tens of thousands who marched through London last Saturday calling on the Government to accept more refugees, there is no clear upward limit to the number of refugees we should take in Britain. (Despite Corbyn’s belief that our social infrastructure is on its last legs thanks to Tory austerity!)

Would 300,000 be enough —roughly the number we accepted from the Balkan conflicts 20 years ago? Half a million? A million?

A man with a head injury is carried by another migrant after violence has broken out between Syrians and Afghans this afternoon

Some of those marchers were modern versions of the intellectuals mocked by George Orwell for disdaining Britain while attaching themselves uncritically to the Soviet Union or other ‘progressive’ national causes.

Many, however, are genuine idealists, distant descendants of the earnest, righteous souls who helped to end slavery, kept a check on the excesses of empire, pressed for female suffrage and ended the death penalty.

No doubt some of those who marched believe we have an equal moral duty to all humans. Yet, if we did, we would have to favour completely open borders, and our resources — both emotional and financial — would be spread too thinly to make a real difference to anyone’s life.

The decent, and realistic, view of the majority in Britain is that we in rich countries do have some obligations to those less fortunate than us, but those obligations are weaker than the ones we owe to our families and friends, to our communities and to our nation.

For societies are not random collections of individuals who happen to live together. Successful nations are based on habits of co-operation, familiarity and trust, and on bonds of language, history and culture. If the European nations — so attractive to these refugees — are to survive and flourish, we require some sense of favouring our fellow citizens, and of controlling who crosses our borders to become a new citizen.

But Europe in recent years has been moving rapidly in the other direction in respect of its internal borders. Free movement across EU countries, which was once barely noticed because of similar income levels across the union, burst onto public consciousness after the poorer post-communist societies joined in 2004.

M eanwhile, little attention was paid to Europe’s external borders because — despite huge income gaps with most of the rest of the world — few people from poor countries tried to reach its shores.

Thanks to the Syria crisis, this has changed irrevocably, and the initial response of European leaders, cocooned in their borderless ideals, has been alarming.

By effectively abandoning the selection of who should and should not be allowed in at Europe’s southern and eastern borders, we are not showing compassion to the wretched of the earth. Instead, we are encouraging a dangerous free-for-all in which the fittest and nimblest — generally young men — battle their way in.

Tensions boiled over as huge groups of migrants waited to board trains at Beli Manastir in Croatia his afternoon. Police are pictured running for cover

They are the kind of dynamic, determined, often educated people that the conflict-ridden societies they left behind need to rebuild them when peace at last arrives.

Most people in Britain and the rest of Europe, faced with pictures of desperate people, do feel compassion — and many act on it as individuals by donating to charities.

But most of us want to be generous without encouraging further flows, and without damaging our own country’s social infrastructure with unsustainably large inflows of people. Britain is already struggling to properly integrate incomers from more traditional, often Muslim, societies.

That is why I believe David Cameron’s ‘head and heart’ approach is broadly right. No doubt we can, and should, take a few more Syrians than the 20,000 over five years he has mooted. But our Government’s approach of investing more in the Syrian refugee camps to make them better places to live for a few years is surely right.

Most Syrians coming to Europe have been arriving from those camps in Turkey, Jordan and Lebanon, not because their lives are in any immediate danger, but because the UN refugee agency is running out of money to make them tolerable places to live.

They need more investment in schools and clinics and why not encourage businesses too?

But in the short term, we need to be far more ruthless about turning people away at Europe’s borders — maybe processing them in the way that Australia does, outside our borders, in the refugee camps themselves.

This will produce dismaying TV footage and Europe will be accused of heartlessness, but once the message gets through, it will cut the flows and reduce deaths on the Mediterranean. It will allow us to select those in most dire need, and those who are proper refugees under the narrower ‘well-founded fear of persecution’ formula dating from 1951.

In the medium term, we need to make foreign aid work better. We need more effective military interventions to stop future conflicts like the one in Syria.

That is easier said than done, but safe havens enforced by Western air power worked in northern Iraq in the war against Saddam, so why could something similar not become the norm in conflict zones?

Instead of reflecting along these lines, EU leaders are, as usual, fretting about trying to impose a ‘single European response’ — in this case a fair sharing out of the burden of taking in those refugees already in Europe.

But how do you define fair? These issues are — like security and defence policy — of fundamental concern to many countries in the EU which have different histories and national psychologies.

Hungary has announced plans to build a giant fence along the Croatian border - just days after sealing off access from Serbia with a 100 mile razor-wire barrier (pictured)

Even before this crisis emerged, Britain was experiencing unprecedented levels of legal immigration, and a rapidly rising population.

Partly for that reason we are focusing on financial aid to refugee camps and increasing development aid, rather than throwing open our borders like Angela Merkel has in Germany. One of the reasons she did is that Germany has a sharply falling population.

Yet it is the East Europeans who are most understandably upset about Brussels’ attempt to impose a kind of compulsory cosmopolitanism across the EU. Many in the former communist countries tend to see themselves as victims of their rapid social transitions. This makes them less likely to regard incoming foreigners as victims.

Most East European countries are much more ethnically homogeneous than western Europe, and wary of changing that. Some are also suffering a ‘demographic panic’: their birth rates are plunging and many of the educated have moved west — Bulgaria’s population is expected to fall by almost a third by 2050 — but they do not want their empty villages filled with Syrians and Afghans.

Many British and European citizens have expressed commendable empathy over the refugee crisis. But that has encouraged the politics of moral gesture, rather than clear-eyed leadership from Europe’s political class.

We cannot take the millions who would like to come here for a better life. It is far better to admit that and to restore the integrity of Europe’s borders — while selecting those in greatest need of help — than to make promises we do not really mean, and then renege on them. (On any objective basis of global need, Syrian refugees in camps come quite low. A child still dies every minute from malaria.)

In a telling radio interview, Bob Geldof said: ‘I hate what this is doing to us.’ He was agonising over the fact our bluff has indeed been called and we are unable to live up to our foolish if well-intentioned promises.

The offer to provide protection to anyone in the world suffering ‘serious harm’ cannot be fulfilled. A more lasting and realistic refugee policy is urgently required, but it will not be a pretty sight

David Goodhart is author of The British Dream, about post-war immigration, and director of Demos Integration Hub

The migrants’ determination follows Mrs Merkel’s contentious announcement a few weeks ago that all Syrians would be welcome in her country

Nightmare on the Migrant Express...

From Sue Reid in Croatia

A picture of his heroine, German Chancellor Angela Merkel, is pinned to a tree beside him as he sits on a patch of grass outside a migrants’ hostel in the middle of Europe.

Bearded Syrian Abu Nordine waves his arm at our camera to show off his wristband with the word Germany emblazoned in red on it.

He’s determined to get there, yet at eight in the morning on Thursday this week he was still stuck in Croatia, along with thousands of other migrants.

As the hot morning wore on, more migrants kept arriving at the hostel near the centre of Zagreb, the Croatian capital.

They had come through Serbia and, after being turned back at Hungary’s border by police with tear gas and water cannon, they’d chosen an alternative route to Germany through Croatia.

Ahead lay Slovenia, which immediately said any illegal migrants would not be let in and sent riot police to the border to stop them getting through.

‘We will get to Germany one day soon,’ said 38-year-old Abu who claimed to have fled Syria’s capital Damascus after his two children were killed in the country’s brutal civil war. ‘We don’t want to stay in Croatia, and they don’t want us here either,’ he added.

The migrants’ determination follows Mrs Merkel’s contentious announcement a few weeks ago that all Syrians would be welcome in her country. It caused a tidal wave of migrants which has overwhelmed the EU. Unable to cope with the new arrivals, Germany abandoned Europe’s free borders policy and temporarily shut its borders with Austria, before introducing a tougher migrant-vetting regime.

Austria, Slovakia and Holland have also all pledged tighter border controls, while Croatia says it is ‘absolutely full’ and has closed seven of its eight border crossings with Serbia as well as the roads leading to them.

The anarchy now tearing the EU apart is a huge embarrassment for Mrs Merkel whose promise to welcome all Syrians immediately turned the migrant problem into a full-blown crisis — and Croatia is now the front line.

Day by day, the migrants are growing more militant. At the Zagreb hostel on Thursday some of the 500 inmates threatened to riot when they found they would be stuck in Croatia because the border with Slovenia was being closed.

A number of young men threw toilet rolls out of the windows, shouting Arabic and English obscenities, and became so threatening that riot police were called.

At the same hostel, I watched hundreds refuse to claim asylum in Croatia because they wanted to do so in Germany. In response, they were handed an official looking document by Zagreb immigration police stating they must leave the European Economic Area (EEA) within 30 days.

With the papers still in their hands, 60 of them then walked out of the hostel’s grounds and down the road as the police watched.

‘We are going to Slovenia’, said Halian Hannad, a 34-year-old father of five children, aged between ten and two, who, he told me, are still in his home town of Raqqa, now controlled by ISIS. ‘That is the route to Austria and Germany.’

The 60 migrants walked as far as the bus stop, and then took a ride to the train station.

They bought £7 one-way tickets to Slovenia’s capital Ljubljana and, at 6.37 pm climbed on board. By then they had been joined by nearly 100 other migrants — men, women and a handful of children who had arrived in Zagreb earlier in the day from the border with Serbia.

Outside at the station café, the barman looked on in amazement. ‘We had not seen any migrants in Zagreb until today but we hear thousands more are coming,’ he said. ‘I run a nightclub, and we have brought in extra security staff because there are so many young men with different customs and attitudes to women among them.’

None of this, of course, was of any interest to the migrants on the train as it pulled out towards Dobova, the first town on the Slovenian side of the border with Croatia.

Photographer Jamie Wiseman and I were the only journalists on board. Our fellow passengers grew increasingly excited as the train picked up speed.

They thought they had escaped Croatia and would soon be in Germany.

But then, soon after 7pm, the train was held at Dobova station. On the platform and on the tracks, 20 Slovenian police officers and border officials surrounded it.

They climbed on board and checked passengers’ passports, before leaving again. But they were not gone for long. After 30 minutes, with the train still stationary, the police boarded again.

They moved through our carriage saying Syrians must move to the back of the train with their luggage.

‘We have carriages which are especially for you,’ said one smiling police officer in crisp blue uniform and lots of gold braid as he gave me what looked suspiciously like a wink, knowing I was British.

Outside on the platform, Dobermans were paraded up and down by their police handlers. Soon it was all over. Tricked, the migrants found the carriages they were now sitting in had been uncoupled and, as the train pulled out, they were left behind.

When they realised they were stranded, the 150 or so migrants in the carriages refused to accept water brought to them by the local Red Cross. When they tried to jump off the train onto Slovenian territory, they were pushed back inside by police and dogs. In the dark of the night, the disgruntled migrants in the two carriages were towed back to Zagreb.

After the incident, trains running between the two capitals were stopped. And Slovenia said it would not allow illegal migrants to pass through to Austria and Germany, although genuine asylum seekers would be allowed through in line with EU rules.

By yesterday, the Slovenians had stepped up road checks near Dobova, using a helicopter as well as foot patrols in the mountainous region.

‘We will return the migrants to Croatia in the shortest time possible,’ said Anton Stubljar, the Slovenian police official in charge of the operation.

But the fact is that, as I witnessed this week, Croatia is unable to cope with the enormous influx of people — 9,000 are estimated to have arrived on Wednesday alone, and more than 15,000 this week. The two migrant reception centres I visited in and near Zagreb were overflowing by midday on Thursday and still more were arriving.

Further south in Tovarnik, on Croatia’s border with Serbia, a stand-off between migrants and police had grown ugly. Amid desperate scenes at the town’s railway station where migrants who had managed to cross into Croatia had gathered, almost 5,000 had been left stranded overnight after promised trains to Zagreb did not arrive.

Children screamed and women cried as they waited hours before being pushed onto buses for the Zagreb migrant camps. Groups of migrants, almost all of them young and fit-looking men, broke away from the police and set off on foot down railway lines and through fields.

‘They want to take us to the camps, but we don’t want that,’ said Ismail Hussen, claiming — like all the others I asked — that he came from Syria. Whatever the truth of this — and an official EU report released yesterday says only one in five of them is from Syria — the migrants were still trying to get to Germany from Croatia yesterday.

In Zagreb, hundreds continued to wait in vain at the train station, hoping to leave Croatia.

As locals in this staunchly Roman Catholic nation walked by, they stared in astonishment at the newcomers, some of whom were wearing burkhas and full Islamic robes. For their part, the migrants returned the stares with looks of open defiance.

Other migrants yesterday morning were hiring taxis for Slovenia — only to be stopped at the motorway border-post by Croatian police.

Women in hijabs clutching children stood beside the road in tears and men furiously argued with officials who told them they had to go back as Slovenia would not accept them.

By last night at this border, Slovenia had sent phalanxes of riot police to deal with a growing crowd of migrants running amok.

They were carrying shields, and barricading the border-crossing with wire as lines of hundreds of migrants walked towards them.

At another point on the border with Slovenia, seven miles from Zagreb, a river called the Bregancica divides the two countries. It passes through villages on both sides of the border which are linked by mountain footpaths and narrow bridges.

When I visited yesterday, I spoke to the landlord of a hostelry right next to the river on the Croatian side. I asked him if he expected migrants to escape over to Slovenia by walking.

‘I live in a village just over the river in Slovenia,’ he explained. ‘This summer I have seen African and Middle Eastern migrants running through my own front garden as they slip over the bridges.

‘The border police can’t be everywhere. Up to now, there have been just a few using this route to get through to northern Europe. Soon, I expect, it will be many more.’