When Athens went to war with Sparta some 2,500 years ago, the Greek historian Thucydides identified one simple cause- a rising power threatened to displace a ruling one, leading inexorably to conflict. As Graham Allison explains, in the past 500 years, great powers have found themselves in 'Thucydides's Trap' sixteen times. In twelve of the sixteen - from war between the French and the Hapsburgs in the sixteenth century to the two world wars of the twentieth - the results have been catastrophic. Today, the same structural forces propel China and the United States toward a cataclysm of unseen proportions, even as both sides insist that such a war could never occur. In Destined for War, Allison compares the U.S.-China conflict to its closest parallel- World War I. There, a rising Germany threatened the supremacy of the British Empire. He sketches several scenarios in which America and China might slide, against their intent and better judgment, into a similar conflict. But he also examines the rare instances when two clashing powers have avoided disaster, and speculates about whether the current standoff could be one of those exceptions.