In the autumn of 732, Flags with Qur’anic verses proclaiming the glory of God’s revelation to Muhammad could be seen for miles around the French city of Tours. A Muslim army marched on a path of conquest that seemed destined to reach the ends of Europe. As Edward Gibbon said, but for a few unlucky battles, “the interpretation of the Koran would now be taught in the schools of Oxford, and her pulpits might demonstrate to a circumcised people the sanctity and truth of the revelation of Mahomet.”

Yet the march of Islam began to recede after suffering a defeat at the hands of the Franks. The ensuing seven hundred years brought the disintegration of Muslim power in Western Europe, finally resulting in the surrender of Granada in 1492. Frankish King Charles Martel may have saved Europe from Muslim conquest, but a more subtle invasion of the continent had begun. Low birthrates among Europeans and soaring immigration rates may result, as historian Bernard Lewis suggests “[in] a Muslim majority by the end of the twenty-first century at the latest.”

The Western world now has an astonishingly-low fertility rate; families are simply not producing enough children to maintain even their current populations. The average European birthrate is 1.38 children per woman, a far cry from the rate of 2.1 needed to prevent population decline. Explanations for this phenomenon vary, but a general premise suggests that the pressures of modern life render having large families as an unnecessary burden. One cannot forget that today’s solutions can lead to tomorrow’s problems, for if the current fertility rate remains, the population of Europe will shrink from 728 million to 207 million by the end of the century.

While earlier demographic disturbances, such as plagues and famine affected all segments of the population, the current trend is only reducing the number of young people within Western society. As the elderly account for a larger proportional share of the native European population and lifespans continue to increase, only a great influx of immigrants can maintain the current workforce and the entitlement programs for retirees. Millions in North Africa and the Middle East have responded, migrating to Europe in search of economic opportunity. Few European Muslims are advocating widespread integration into Western culture, instead placing emphasis on multiculturalism within historically-homogeneous nation-states. Dyab Abu Jahjah, a prominent Belgian Muslim, is actively campaigning in Antwerp to add Arabic as an official language of his country, referring to the notion of assimilation as “cultural rape.”

As French and Dutch voters headed to the polls to vote on the EU Constitution, the potential admission of Turkey as a member state weighed heavily in their minds; by admitting Turkey, the EU would open the floodgates to expanded Turkish immigration. In Berlin, kabob shops already outnumber traditional German sausage eateries as Muslims form a growing proportion of the German population. Angela Merkel, who was recently elected chancellor, summarized the thoughts of many Germans regarding Turkish immigration: “we don’t say they should not be Muslims. But we do say that we are a country with a Christian background, and Turks must understand this…Try opening a Christian church in Istanbul.”

Soaring immigration rates are accompanied by a high birthrate among European Muslims relative to the general population, with some estimates reporting that Muslims already constitute about 25% of French schoolchildren. If the current trends continue, an Islamic majority might surface in France and the Netherlands as early as 2040. Unless governments throughout the continent adopt effective assimilation policies and the fertility rates increase dramatically, population demographics may accomplish what the Muslim army on the field of Tours could not-the Islamic conquest of Europe.