Does history repeat itself? Toward the end of the 19th century the United States, having survived a terrible civil war, made the transition from an agrarian to an industrial economy and emerged as a serious rival to the great powers of Europe. In the first half of the 20th century it grew to overshadow them all, economically and militarily, and become the richest, most powerful and most influential country in the world.

A century after the American Civil War ended, the People’s Republic of China, still a very poor country in the 1960s and something of an outcast in international politics, endured a so-called “Cultural Revolution” that threatened to tear it apart. Immediately afterwards, in the 1970s, it achieved a rapprochement with its bitter enemy, the United States, was seated at the United Nations and began to move away from a centrally planned economy toward a form of capitalism. Like the United States a century earlier, it then entered a Gilded Age of unprecedented economic and industrial growth, continuing to the point where it will soon displace the United States as the world’s largest economy, if it has not already done so.

As a result of these developments, few would dispute the proposition that a Sino-American bipolarity in international relations has replaced the Soviet-American bipolarity known as the Cold War that lasted for almost half a century, from 1945 to 1991. This in turn raises two important questions. In a bipolar world, is hostility between the two greatest powers inevitable? And if it is, will the hostility inevitably lead to a major war between them, which nowadays would exceed in death and destruction the so-called “world wars” of the first half of the 20th century?

The Soviet-American precedent might suggest that the answers are yes and no, respectively. The Cold War was certainly marked by plenty of hostility between the then two superpowers, but a major war was averted, although the world came close to one in 1962 and although some Soviet military personnel did fight, secretly, against the Americans in both Korea and Vietnam.

The Cold War was originally a contest about the future of Europe and especially of Germany, which had been left in dispute after the defeat of the Nazis, but its most dangerous moment came when the Soviets penetrated the American sphere of influence in the Caribbean. The Sino-American rivalry (Cold War II, so to speak) seems likely to find its most dangerous flashpoints in two messy pieces of unfinished business left over from the American war against Japan: the unnatural division of Korea and the ambiguous status of Taiwan.

Viewed in retrospect, both situations are the result of serious mistakes made by the United States between 1941 and 1945. Korea was divided because the Americans thought, erroneously, that they would need Soviet help to defeat Japan. Taiwan, which should have become an independent state after it was detached from the Japanese Empire, was instead promised to the moribund regime of Nationalist China and became the last stronghold of that regime after it lost the civil war on the mainland.

Perhaps in the 1950s a tradeoff could theoretically still have been arranged: give Taiwan to the Chinese Communists in return for giving North Korea to South Korea. That is a solution that might have appealed to Richelieu, Metternich or Bismarck. But now that Taiwan, despite unpromising beginnings, has become a successful democracy, it would be unthinkable for the Americans to abandon it to its fate. Meanwhile, China covets both South Korea and Taiwan as part of its natural sphere of influence or, in the case of Taiwan, as part of Chinese territory.

In his classic account of the war between Athens and Sparta, Thucydides, an Athenian who lived through that war, asserted that the danger of war between two dominant powers is greatest when the balance of power between them is shifting from one to the other, a situation that has acquired the label of “Thucydides’s trap.” Since China is obviously gaining power today while the United States is (relatively) losing it, this seems to suggest that we are entering the period of maximum danger. Another conclusion Thucydides drew is that the situation becomes particularly dangerous when one of the two great powers seems to threaten a small ally of the other great power. Taiwan and the two Koreas come to mind.

Graham Allison, an American political scientist who made his reputation in 1971 by publishing an analysis of the Cuban Missile Crisis, has tried in a recent book to apply these insights to the Sino-American situation.1 With some of his colleagues and students at Harvard, he has undertaken a research project in comparative history, focusing on the problem of “Thucydides’s trap” as illustrated by 18 case studies, from Athens and Sparta in classical times to China and the United States today.

His book summarizes the results of the other 16 case studies, 12 of which led to war, with the originally dominant power winning five wars and the rising power winning seven. The originally dominant power also won in the Soviet-American Cold War, which was decided without a major war, while the rising power won in the three other cases that were settled without a major war, so the actual score is ten to six for the rising powers (ten to seven if the war between Sparta and Athens is counted, since Sparta, the originally dominant power, won). Allison seems to think that China’s rise to dominance is inevitable but he thinks that war between China and the United States may (or may not) still be avoided.

All of this is interesting. However, the number of cases is too small to produce a scientifically valid result, in some cases the outcome was more ambiguous than Allison suggests, and his list of cases is not exhaustive. (One interesting case that he fails to mention is the American Civil War, which the previously dominant South started as a last desperate and unsuccessful effort to prevent the rapidly growing North from taking over control of the country.) Allison also fails to distinguish clearly between cases where the rising power really was overtaking the dominant power, or had already done so, and cases where the previously dominant power overestimated the threat to its position. Not surprisingly, the rising power is more likely to win contests of the first kind, whether through war or otherwise, than of the second.

Two of Allison’s cases deserve more careful study than most of the others, since their circumstances have the most striking parallels with the present Sino-American contest. The first is the Anglo-German rivalry prior to 1914, which led to a major war, and the second is the American-Soviet Cold War, which did not. In the first case the two rivals had much in common. Both were in gradual transition from a premodern form of government to modern democracy – the British were slightly further along the road to democracy than the Germans, but not as much further as wartime propaganda would later suggest. Their languages and their established Anglican and Lutheran churches were similar, their royal families were closely related and they had similar problems with ethnic (and Catholic) minorities: the Irish and the Poles.

Yet they went to war. The British worried about the rise of Germany and felt the need to protect France and Belgium; the Germans worried about the rise of Russia and felt the need to protect Austria-Hungary, their only ally; and the Russians felt the need to protect Serbia, which was involved in the assassination of the heir to the Austro-Hungarian throne.

In the second case the Americans and Soviets had little in common, culturally, politically or economically, yet they avoided going to war. Perhaps their leaders were more skilful or luckier than their British and German counterparts in the earlier contest. A more likely explanation is that the existence of nuclear weapons, and personal experience by the policymakers of what total war had meant in practice, even without nuclear weapons, made them more cautious. Nuclear weapons of course are even more terrible today than during the Cold War, so we can hope that the caution is still there. But the Chinese leaders today were born after the end of their civil war, and the last four American presidents have had no experience of real war, in contrast to most of their predecessors who held office during the Cold War.

Fortunately it is hard to imagine present-day American leaders, armed with thermonuclear weapons, starting a war in an effort to reverse the apparent course of history, as the Confederates did when they fired on Fort Sumter in 1861. On the other hand the sinister regime in North Korea seems crazy enough to risk such a war, and South Korea and Taiwan are vulnerable hostages to fortune today, as Serbia, Belgium and Austria-Hungary were in 1914. So there is definitely no reason for complacency.


1 Destined for War: Can America and China Escape Thucydides’s Trap? (Boston and New York: Houghton Mifflin, 2017).