In the past one hundred years, four successive political movements—Prussian militarism, German Nazism, Japanese imperialism, and international Communism— mounted military campaigns to conquer Europe, Asia, and the world. Had any of them prevailed, it would have been a profound loss for civilization as we know it. Yet over the course of these bids for power, a coalition headed first by Britain and then by the United States emerged not just to oppose but to destroy them utterly.

From the long perspective of human affairs, these victories must stand as among the most remarkable of the past three millennia. They were as decisive for world history as the victories of the ancient Greeks over Persia, of Rome over Carthage, and of the Franks over the Umayyad Caliphate.

Moreover, military triumph has been complemented by economic success. The policies of free-trade liberalism, which in the nineteenth century made ...