Power Play.

• Author: Heilbrunn, Jacob
• Position: The Realist - U.S. President Donald Trump's foreign policy - Viewpoint essay

On November 11, Europe will mark the 100th anniversary of the end of World War I. Though it has been overshadowed by World War II in popular memory the Great War, as it was known, signified a turning point for Europe and America in the past century. Whether they sleepwalked into the cataclysm or actively sought it out, the monarchs of Europe inadvertently ushered in a new age of great power conflict that defied contemporary liberal predictions that growing interdependence would avert a renewed threat of war. To look back at the war is to realize that it has as much to say about the present as the past. What happened once could happen again.

It would be difficult to think of a more catastrophic moment for the West, which has never fully recovered from the conflict. On its eve, the British journalist Norman Angell had published a bestselling book called The Great Illusion that declared that a European war was unthinkable. Free trade, as the nineteenth-century liberals William Cobden and John Bright had argued, would help to ensure that nations cooperated with each other and shunned armed hostilities as inimical to prosperity. A war, by contrast, would mean, as Angell wrote, that "the incentive to produce would be sapped and the conquered area be rendered worthless. Thus, the conquering power had to leave property in the hands of the local population while incurring the costs of conquest and occupation." Instead, nations should submit their grievances to be arbitrated by a world court. Interdependence and globalization would ensure an irenic future.

It never happened. Instead, the guns of August created a protracted bloodbath that ended up toppling, one after another, the monarchies of the continent. The Romanovs were assassinated. Kaiser Wilhelm II fled to Holland, where he lived at Huis Doom. The Austrian Emperor Franz Joseph Karl and his consort Zita were exiled to Funchal, Madeira. While England's monarchy emerged intact, its imperial aspirations did not.

No sooner had hostilities ended than a new battle began over the Kriegsschuldfrage, or war guilt question. It seemed inconceivable that such a calamity could have originated solely from the assassination of an Austrian archduke and his morganatic wife in Sarajevo. After the conflict ended, the victors pinned the blame on Germany, codifying its culpability in Article 231 of the 1919 Treaty of Versailles. British Prime Minister David Lloyd George had said he wanted to squeeze Germany "until...