For many people the end of the 20th Century was 'the triumph of the West'. Writing in 1989, Francis Fukuyama argued that the crumbling of Soviet Communism marked 'the end of history'. Capitalism, liberalism and democracy had emerged as the victors of the century's protracted ideological conflicts.
Yet the extreme violence of the 20th century had been caused by much more than clashes of ideology. Ethnic conflict, economic volatility and empires in decline: these were the factors that had generated so much conflict and cost so many millions of lives. And events dating back 10 years before the fall of Communism pointed to a recurrence of what I have called 'The War of the World'.
The year 1979 brought a woman to power in England, a woman wholly committed to the idea that salvation lay in the free market. (Mrs Thatcher, it might be said, was one of the root causes of the subsequent Soviet crisis.) But 1979 also brought the Ayatollah Khomeini to power in Iran, a man just as committed to the idea that salvation lay in the teachings of the Prophet Mohammed.
One leader read Friedrich Hayek's The Road to Serfdom, the other the Koran. One revolution pointed to a world based on free trade, the other to a world based on holy writ.
There were many reasons why Iranians rallied to a leader who routinely denounced the United States as 'the Great Satan'. In 1953 it had been the CIA (along with MI6) that had overthrown the popular Prime Minister Mohammad Mossadeq and installed Shah Mohammed Reza Pahlavi as a dictator. The Shah's regime was by no means the most vicious the United States bankrolled during the 1960s and 1970s; nevertheless, his combination of private hedonism and public repression sufficed to put a powder keg under the Peacock Throne.
The Iranian revolution of 1979 was partly a matter of settling scores against the Shah's military and secret police. But under Khomeini's leadership its main goal became to turn back the clock; to purify Iranian society of every trace of Western corruption. It also aimed to challenge American pretensions throughout the Islamic world.
As a religion, Islam is of course far from monolithic. There are deep divisions, not least between the Shiites who predominate in Iran (and Iraq) and the Sunnis who predominate in the Arab countries. But 'Islamism' was a militantly political movement with an anti-Western political ideology that had the potential to spread throughout the Islamic world, and even beyond it.
Ironically, the United States had a hand in its spread. The Soviets found their occupation of Afghanistan so difficult to sustain because they found themselves fighting a new and highly motivated foe, the mujahideen, armed and trained by the CIA on the principle that my enemy's enemy is my friend.
And which regime has done more than any other to spread the teaching of Islamic fundamentalism since 1979? The answer is Saudi Arabia, the United States's most important ally in the Arab world. For it was not the poor of the Middle East who rushed to join the jihad; often, it was those who had received a Western education.
The greatest of all the strengths of radical Islam, however, is that it has demography on its side. The Western culture against which it has declared holy war cannot possibly match the capacity of traditional Muslim societies when it comes to reproduction. The Islamic revolution ended at a stroke the Westernisation of female life in Iran.
As dictated by a strict interpretation of Sharia law, they were now forced to veil themselves with the hijab in all public places. Strict segregation of the sexes was introduced in schools and public transport. Female presenters, actresses and singers were banned from radio and television. Women were prevented from studying engineering, agriculture and finance. They were systematically purged from all high-level government positions as well as the judiciary. In December 1979 the former minister of education, Farrokhru Parsa, was executed, having been convicted of promoting prostitution, corrupting the earth, and 'warring against God'. Contraception and abortion were banned and the age of consent for marriage lowered to just 13.
The constitution of the Islamic Republic spelt out unambiguously the proper role of women in the new theocracy:
The family unit is the basis of society, and the true focus for the growth and elevation of mankind... Women were drawn away from the family unit and [put into] the condition of 'being a mere thing', or 'being a mere tool for work' in the service of consumerism and exploitation. Re-assumption of the task of bringing up religiously minded men and women, ready to work and fight together in life's fields of activity, is a serious and precious duty of motherhood.
Such attitudes help to explain why, although the average fertility rate in Muslim countries did decline from the 1970s onwards, it remained consistently more than twice the European average.
Though far from being a feminist, Margaret Thatcher embodied a profoundly different social change that went hand in hand with the liberalisation of the Western economies in the late 20th century. With the decline of traditional trade unions and the introduction of flexible working practices, it became easier for British women to enter the workforce. Legislation against sex discrimination opened up all kinds of careers to them. And the ready availability of contraception and abortion in the West gave women an unprecedented control over their own fertility.
The two things went together. Women wanted to work, or maybe economic pressures obliged them to work. It was much harder to work with three or four children to look after as well; so women opted to have just two, or one, or - in the case of many of the most professionally ambitious - none at all. From the late 1970s, the average West European couple had fewer than two children. By 1999 the figure was just over 1·3, whereas, for a population to remain constant, it needs to be slightly over two.
Europeans, quite simply, had ceased to reproduce themselves. The United Nations Population Division forecast that if fertility persisted at such low levels, within 50 years Spain's population would decline by 3·4 million, Italy's by a fifth. The overall reduction in 'indigenous' European numbers would be of the order of 14 million. Not even two World Wars had inflicted such an absolute decline in population.
The consequences of these two opposite trends were dramatic. In 1950 there had been three times as many people in Britain as in Iran. By 1995 the population of Iran had overtaken that of Britain. By 2050, the population of Iran could be more than 50 per cent larger. At the time of writing, the annual rate of population growth is more than seven times higher in Iran than in Britain. A hundred years ago - when Europe's surplus population was still flocking across the oceans to populate America and Australasia - the countries that went on to form the European Union accounted for around 14 per cent of the world's population. By the end of the 20th century that figure was down to around 6 per cent, and according to the UN by 2050 it could have fallen to just 4 per cent. That begged at least one awkward question: who was going to pay the taxes necessary to pay for Old Europe's generous state pensions?
With the median age of Greeks, Italians and Spaniards projected to exceed 50 by 2050 - one in three people in each of these countries would be 65 or over - the welfare states created in the wake of the Second World War looked obsolescent. Either new-born Europeans would spend their working lives paying 75 per cent tax rates, or retirement and subsidised health care would have to be scrapped. Alternatively (or additionally), Europeans would have to tolerate substantially more legal immigration. The UN estimated that to keep the ratio of working to non-working population constant at the 1995 level, Europe would need to take in 1·4 million migrants a year from now until 2050. The annual figure for net migration in the 1990s was 850,000.
But where would the new immigrants come from? Eastern Europe alone could not supply anything like the numbers needed. Indeed, the UN expected the population of Eastern Europe to have declined by a quarter by 2050. Those who feared waves of migrants from Eastern Europe were facing the wrong way - east instead of south. The reality was that Europe's fastest growing neighbours by the end of the 1990s were, for the reasons discussed above, countries that were predominantly if not wholly Muslim.
Consider Morocco, where the population growth rate is seven times higher than in neighbouring Spain. At the very northernmost tip of Morocco, directly opposite Gibraltar, lies the tiny Spanish enclave of Ceuta, one of the few surviving remnants of Spain's imperial past. Today, however, it is no longer an outpost of an aggressively expansionist European empire, but a defensive bulwark maintained by a continent under siege. Camped outside Ceuta are thousands of people from the Maghreb and beyond, some fleeing zones of conflict, others simply seeking better economic opportunities. Here they sit for days, waiting for a chance to sneak past the Spanish border patrols. The European Union has responded by subsidising the construction of a five-mile border fence, equipped with razor wire, watchtowers and infra-red cameras.
European officials admit that they have no idea how many people are making their way illegally into Europe. About 50,000 illegal immigrants are seized at Europe's ports or at sea every year, but it is impossible to say how many get through or die in the attempt. Every week Spanish police patrolling the waters between Africa and Europe catch dozens of people, most of them Moroccans, trying to sneak into southern Spain or, further south, the Canary Islands, in small smuggling boats known as pateras. For those who survive the journey, the Spanish town of EI Ejido is the point of entry into Europe. In the asphyxiating heat of the greenhouses there, 20,000 immigrants work in conditions that few Spaniards are willing to endure.
El Ejido is just one manifestation of what some call Eurabia. A youthful society to the south and east of the Mediterranean is quietly colonising, in the original Roman sense of the word, a senescent and secularised continent to the north and west of it. Today, at least 15 million Muslims have their home in the European Union, a number that seems certain to rise. The historian Bernard Lewis's prophecy that Muslims would be a majority in Europe by the end of the 21st century may go too far, but they may well outnumber believing Christians, given the collapse of church attendance and religious faith in Europe.
Predictably, the growth of Muslim communities has generated some resentment on the part of what we might call the old Europeans. There is clear evidence that whatever the economic benefits of immigration there are also real costs for unskilled indigenous workers.
Periodically, violence flares up. There are attacks on the immigrants; sometimes on their mosques. In the eastern outskirts of Paris in 2005 disaffected youths from predominantly Muslim immigrant communities ran amok after two of their number died while hiding from the police. The fact that a minority of European Muslims - not all of them first-generation immigrants - have become involved with extreme Islamist organisations adds to the mutual antagonism. Once, Spaniards and Britons alike had to worry about terrorism by nationalist minorities. The attacks in Madrid in March 2004 and on London in July 2005 have made it clear that there is a new enemy within.
In the 52nd chapter of his Decline and Fall of the Roman Empire, Edward Gibbon posed one of the great counterfactual questions of history. If the French had failed to defeat an invading Muslim army at the battle of Poitiers in 732, would all of Western Europe have succumbed to Islam? 'Perhaps,' speculated Gibbon with his inimitable irony, '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.'
The idea was to amuse his readers, and perhaps to make fun of his old university. Yet today work is all but complete on the new Centre for Islamic Studies at Oxford, which features, in addition to the traditional Oxford quadrangle, a prayer hall with a dome and minaret tower. That fulfilment of Gibbon's unintended prophecy symbolises perfectly the fundamental reorientation of the world which was the underlying trend of the 20th century.
A hundred years ago the West ruled the world as result of centuries of overseas conquest and colonisation. Now little remains of Western imperialism, aside from America's waning military presence in the Middle East and Asia. Then, the frontier between West and East was located somewhere in the neighbourhood of Bosnia-Herzegovina. Now it seems to run through every European city. That is not to say that conflict is inevitable along these new fault lines; history suggests that there may be as many clashes within civilisations as between civilisations in the years that lie ahead. But it is to say that, if the history of the 20th century is any guide, the fragile edifice of civilisation can very quickly collapse even where different ethnic groups seem well integrated.
The 20th century also demonstrated that economic volatility increases the likelihood of such a backlash - especially in the context of the new kind of welfare state that emerged in the first half of the century, with its high levels of redistributive give and take. For ethnic minorities are more likely to be viewed with greater hostility when times are hard or when income differentials are widening.
Finally, it was not by chance that the worst killing fields of the mid-20th century were in places such as Poland, the Ukraine, the Balkans and Manchuria; while extreme violence in the later 20th century shifted to more widely dispersed locations, from Guatemala to Cambodia, from Angola to Bangladesh, from Bosnia to Rwanda and, most recently, Iraq and Sudan. Time and again it has been in the wake of the decline of empires, in contested borderlands or in power vacuums, that the opportunities have arisen for genocidal regimes and policies. Ethnic confluence, economic volatility and empires on the wane; such was and remains the fatal formula. Already we can see the potential for a new conflagration in Iraq, where some would say a civil war between Shiites and Sunnis has already commenced. This is a war that could easily escalate as the Anglo-American military presence is wound down. It is a war that could just as easily spill over into neighbouring states. And who can say what the effects might be of such a Middle Eastern 'Great War' might be on the multi-ethnic cities of neighbouring Europe?
On the eve of the 20th century, H. G. Wells had imagined a 'War of the Worlds' - a Martian invasion that devastated the earth. In the hundred years that followed, men proved that it was quite possible to wreak comparable havoc without the need for alien intervention. The War of the Worlds remains science fiction. The War of the World is, however, historical fact. Perhaps, like Wells's story, ours will be ended abruptly by the intervention of microscopic organisms such as the bird flu virus, which could yet produce a worse mutation and pandemic than that of 1918. Until that happens, however, we shall remain our own worst enemies. We will avoid another century of conflict only if we understand the forces that caused the last one - the dark forces that conjure up ethnic conflict and imperial rivalry out of economic crisis, and in doing so negate our common humanity. They are forces that stir within us still.