In each of my four periods, I argued, conflicts revolved around one or two fundamental issues. From 1559 through 1659, I argued, monarchs in Spain, France, the Holy Roman Empire and England fought in vain to impose their will upon their aristocracies. Conflict in that era combined civil and foreign war, disrupting economies, crippling whole nations, and achieving very little. In the era of Louis XIV (1661-1715), by contrast, war became the province of monarchs. Louis XIV managed to tame his aristocrats and enlist them in his own wars, and indirectly helped his fellow monarchs do the same. He also fought--for most of his reign--for much more limited and achievable goals. His era set the tone for conflict in most of the 18th century, allowing Europe to make remarkable economic, intellectual and artistic progress. In the Revolutionary and Napoleonic era, the ideas of the Enlightenment--that the state could be reconfigured along rationalist lines--unleashed the ambition of monarchs, both to remake institutions at home and extend their power as far as they could abroad.
"The era of the two world wars, I wrote, "witnessed new attempts to transform European society according to abstract principles, with tragic and horrifying consequences." Two ideas--the demand for great empires, most notably within both Imperial Germany and Nazi Germany, and the attempt to create homogeneous national communities all across Central and Eastern Europe--drove the two world wars. They did so even though economic progress was coming far more from international trade than from empires, even for imperial nations like Great Britain and France, and even though the populations of those regions were too mixed to create homogeneous national states without ethnic cleansing and murder on a gigantic scale. But another, deeper problem emerged, relating to the demands of modern democracy. "Modern societies," I wrote, "demand that wars be fought to a brilliantly successful conclusion, and wartime governments have become hostages to realities far beyond their control. ... War has been harder to begin, but also much harder to end, in the era of democracy."
I wrote those sentences with the two world wars in mind, and modern society has changed enormously in the last 70 years. After the Vietnam War, the United States gave up conscription and shrank its army, and most nations around the world have followed suit. Even with anarchy spreading around the world, today's conflicts do not approach the scale of those that began 100 years ago. Yet Vietnam, where the US intervention lasted nearly eight years, showed how hard it was to end even a clearly mistaken war. It took more than half a century to the United States to end its economic war on Cuba, which had had no result. President Obama courageously reached the nuclear deal with Iran, but did not dare even try to resume diplomatic relations And we are now in an age of endless war, comparable, in one sense, to the 16th and 17th centuries. We have begun wars for unattainable objectives, such as functioning democracies in Iraq and Afghanistan--and those wars are more than halfway through their second decade. In an attempt to fight terror, we have spread anarchy. While our capabilities have shrunk, our pretensions have increased: to spread democracy and western ideas of human rights literally all over the globe. And while our public hardly feels the same stake in Iraq and Afghanistan as the European publics did during the First World War, it is much less engaged, and therefore less likely to protest the interminable conflicts.
The dreadful crimes and sacrifices of the Second World War, including not only the Holocaust but also the ethnic cleansing of millions of people by the victors after the war was over, did provide much of the world--and the whole industrialized world--with more than half a century of peace. We are now at sea, with the political order that grew out of that war in headlong retreat in the United States and Britain, and threatened all over the EU. Much conflict lies ahead, and it may be decades before the world achieves a measure of stability. Perhaps by then, a new realism about the possibilities of international affairs will have emerged.