“A modern day mass migration is taking place … that could change the face of Europe’s civilization,” warned Hungarian President Viktor Orban.

“If that happens, that is irreversible. … There is no way back from a multicultural Europe,” said Orban. “If we make a mistake now, it will be forever.”

Orban acted on his beliefs. He erected a 110-mile fence on the Serb border, redirecting hundreds of thousands of migrants away from Hungary to Croatia, thence to Austria and Germany.

Sunday, after a third of a million had passed through, Croatia replaced a center-left with a rightist party. A fortnight ago, the right-wing eurosceptic Law and Justice Party won a landslide victory in Poland.

The Death of the West:... Patrick J. Buchanan Best Price: $2.12 Buy New $12.46 (as of 06:40 UTC - Details) Support for Angela Merkel, who has opened Germany to a million migrants, is plummeting. Bavaria’s CSU, sister party of Merkel’s CDU, is in rebellion. Bavaria has been the main port of entry for the hundreds of thousands of arriving migrants.

Europe is undergoing the greatest mass migration since World War II, when 14 million Germans were driven out of Prussia and eastern Germany and Central and Eastern Europe.

That mass migration halted after two years. But no end is in sight to the migrations from Africa and the Middle East.

As long as Europe’s borders remain open, they will come. And the people who wish to come number not just in the millions but the tens and scores of millions. And they know how to get there.

The routes — through Turkey to the Balkans on land, or across a few miles of the Med to the Greek islands, or from Libya to Lampedusa and Sicily, or into the Spanish enclaves on the Moroccan coast, or out to the Canary Islands — are arduous but not impossible.

Why should they not come?

Why should Arabs and Africans not flee the tyranny, terror, poverty and war that are their lot to come to Europe, live the good life, and have life’s necessities provided for their families by the munificent welfare states of northern Europe? And what is to stop them?

Churchill, Hitler, and... Patrick J. Buchanan Best Price: $9.48 Buy New $14.00 (as of 08:25 UTC - Details) Jean Raspail’s “The Camp of the Saints” is proving more prophetic than Aldous Huxley’s “Brave New World” or Orwell’s “1984.”

Considering the crises facing Europe, the question is no longer: Will the EU survive? It is Orban’s question: Will European civilization survive the century?

This year, the EU monetary union, the eurozone, avoided breaking apart because Athens capitulated and accepted austerity, and the hard-bargaining Germans agreed to a bailout.

How long will Greeks and Club Med members of the EU accept austerity? How long will Germans bail out nations whose people like to work fewer hours while enjoying superior social benefits?

Under the Schengen Agreement, there are to be no barriers to trade and travel, to the movement of goods and people inside the EU.

Yet, across Europe, fences are going up, borders are being re-established, anti-immigrant and anti-EU parties like the National Front of France’s Marine Le Pen, are gaining converts.

If the mass migrations are not halted, the rise of nationalist regimes at the expense of Europe’s liberals and leftists is inevitable.

With birth rates in this smallest and least populated of continents below replacement levels for decades, Europe is aging, shrinking and dying, as it is being invaded and altered forever.

State of Emergency Patrick Buchanan Best Price: $1.99 Buy New $9.99 (as of 06:50 UTC - Details) Optimists point to how America absorbed the 15 million that arrived in the Great Wave of immigration from 1890 to 1920.

But they ignore the differences. America’s immigrants were Europeans from Christian nations coming to a country with a history of assimilation. And the Great Wave stopped in 1924, for 40 years.

Unlike America, Europe has never known mass immigration. And those pouring into Europe are Arab, African and Muslim, not European Christians or Jews. They come from other civilizations and cultures. And they are not all assimilating but rather creating enclaves in Europe that replicate the lands whence they came.

Last year, the Swiss voted to cut back on immigration.

This year, with the UK Independence Party growing in popularity, Prime Minister David Cameron is demanding reforms in the EU charter, before the British vote on whether to leave the EU altogether.

With migrants in the thousands milling around Calais and the entrance to the tunnel to Dover, Brits must be wondering whether it was wise to dig that tunnel beneath the Channel to their island home.

The threats raised by the mass migration into Europe rise to the level of the existential.

Can a civilization survive the replacement of the people who created it by people of other races, religions, and civilizations?

Ask the Native Americans.

Will Europe remain Europe if she is repopulated by Arabs, Muslims, Asians and Africans? What will hold Europe together? Free trade?

In 1981, when Solidarity was crushed by the Warsaw regime on the orders of Moscow, Americans took up the cry — “Let Poland be Poland.”

One day soon, a voice will arise across the Atlantic calling for an end to this invasion, by force if necessary, and declare: “Let Europe be Europe!”

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