Nearly sixty-eight years ago, the last hot war among great, world powers ended. Since then, the world has seen many conflicts, but none that have encompassed the globe. John Gaddis first dubbed this period of relative peace the “long peace”. Surely, this is an era enjoyed by scholars belonging to varying schools of thought in international relations, but not all scholars agree that the long peace will endure. On this one, I’ll side with the realist scholar Kenneth Waltz, who rightly points out, “Every time peace breaks out, people pop up to proclaim that realism is dead.”
In a November 2011 infographic, the New York Times borrowed data from Matthew White’s book, The Great Big Book of Horrible Things, to plot the number of deaths from wars, institutional oppression, failed states, and despots. The infographic lists the ten deadliest wars and intrastate conflicts by percentage of world population killed. There are some shocking statistics, such as this, 11.1% of the global population falling victim to the rule of Genghis Khan, but as one traces the conflicts into the modern era, Bill Marsh notes, “killings as a percentage of all humanity are probably declining.” Indeed, that seems to be the trend since only two events after the year 1900, World War II (which killed 2.6% of humanity) and the rule of Mao Zedong (which killed 1.3% of humanity), made it onto the ten deadliest list. But does the decline in killings as a percentage of all humanity mean we have arrived at a long peace that is to last? The chances are not great that it does, especially looking at the list in a different way.
There is no predicting exactly when the next great power war will happen, but if we calculate the average number of years between the ten deadliest conflicts from the list mentioned above, we see that the gap averages 197 years. There are great wars not included in this list, such as World War I, which would shorten that gap, but nevertheless, it is significant that two conflicts since the year 1900 are included among the ten deadliest of all time, especially when confronting those that argue great power wars are a thing of the past. Sixty-eight years of peace between the major powers is noteworthy, but Waltz would argue, and I agree, that sixty-eight years does not represent a change of the system and “the ominous shadow of the future continues to cast its pall over interacting states.”
In his 2011 book, The Better Angels of Our Nature, Steven Pinker also uses statistics from Matthew White’s research where he constructs a list of the twenty-one “Worst Things People Have Done to Each Other.” Pinker adjusts the death toll for each of these conflicts to a mid-twentieth century equivalent, showing that if some previous atrocities occurred when the global population was much larger, the death toll would far exceed that of World War II. Thus, the argument that wars are becoming less deadly emerges again. This pattern is promising, but not strong enough to argue that a great power war won’t occur again, nor that the next conflict doesn’t have the potential to surpass one of the countries on Pinker’s list. In fact, the data is disturbing because six conflicts from Pinker’s list occurred in the twentieth century and an additional conflict (Congo Free State) continued from the nineteenth century into the twentieth century. That means seven of the twenty-one worst things humans have done to each other have taken place in the last 113 years. That these seven conflicts are not at the top of the list isn’t much of a comfort since together they have killed 150 million people since the beginning of the Congo Free State. A more honest extrapolation from this list is that great wars don’t happen in any predictable pattern, but they do happen. Whether there are just twenty-one years between the conflicts, as in the case of the World Wars, or, if like the current situation, the peace lasts sixty-eight years, the chances of history repeating itself are heavily in the realists’ favor.
It is understood that most of these conflicts were not great power wars and in fact were intrastate wars or internal policies that led to a huge loss of life, as was the case under the rule of Mao Zedong. However, assessing these conflicts from a realist perspective means it is likely that in the modern era an intrastate conflict that approaches anything near killing one percent of humanity, would attract the ire and intervention of great powers. Additionally, in an increasingly interdependent world, an intrastate conflict of the magnitude near that of the conflicts listed above certainly has the promise of creating a great power war. This belief is based on “realism’s five assumptions about the international system,” according to John Mearsheimer. The assumptions are “that the international system is anarchic,” “states inherently possess some offensive military capability,” “states can never be certain about the intentions of other states,” “the most basic motive driving states is survival,” and “states think strategically about how to survive in the international system.”
A possible scenario that could end the long peace is the appearance of new, great powers that “will emerge as the uneven growth process narrows the gap between the hegemon and the eligible states that are positioned to emerge as its competitors.” Christopher Layne argues that this happens either through balancing, where states seek “to correct a skewed distribution of relative power in the international system,” or through the sameness effect, where states, seeking to replicate the hegemon, merely imitate its behavior. The authors of Power Transitions: Strategies for the 21st Century would not disagree with this assessment. They believe the states most likely to do this in the next century are China by 2050 and India by the end of the twenty-first century. Where they might differ with Layne, is that they believe “transitions within regional hierarchies are inevitable,” and that the dominant power will have to “stabilize regions in order to avoid great power intervention.” This is an extremely fine line to walk and the success of the dominant power in doing this rests in a policy that simultaneously intervenes in regional disputes, but also keeps the emerging powers satisfied so as not to start a major power war.
There are those that do believe international institutions have the capability to bring great powers to the proverbial table so that all can walk away satisfied, maintaining the long peace we have enjoyed for sixty-eight years. These same people are often skeptical of the realist’s assumptions and predicted patterns of behavior. Robert Keohane and Lisa Martin criticize Mearsheimer’s idea that, “‘every state would like to be the most formidable military power in the system.’” They point out that no one thinks Switzerland and Argentina want to be the dominant power. But they fail to mention a time when Switzerland and Argentina had the window of opportunity to become the world’s dominant power and declined that role. That is because that window never existed for either of those countries and a realist would argue that given the chance/s, it is inevitable that Argentina and Switzerland would have made a move to become a global power if they had the capability to do so. Continuing to criticize the realist perspective, Keohane and Martin mention that even the United States “could reasonably have expected to become the most powerful state in the world, but did not seek such a position” during the interwar period. This was true for twenty-three years, but given enough chances, a country will try to assume the title of great power or global hegemon if it has the capability. The United States did exactly that following World War II and it hasn’t expressed any interest in relinquishing that title since.
In a 1990 paper, John Mueller likened major war as falling out of fashion like dueling and slavery, but he fails to mention that both of those practices continue to this day in the form of gang violence and sex trafficking, to name two. He writes, “If war, like dueling, comes to be viewed as a thoroughly undesirable, even ridiculous, policy, and if it can no longer promise gains, or if potential combatants come no longer to value the things it can gain for them, then war can fade away.” But the realist contention with this argument is that great powers, even moderate powers, will always desire their security and thus always view war as a viable option as long as they aren’t willing to give up their land and sovereignty to a dominant power. Mueller’s larger argument suggests that war has fallen out of favor with the great powers, especially following World War I, when “the notion that the institution of war, particularly war in the developed world, was repulsive, uncivilized, immoral, and futile” took hold as a powerful idea, one that the victors of WWI were committed to. But then what happened with World War II? His answer, the European powers understood that war was bad after WWI, but it took WWII for Japan to get “the message most Europeans had received from WWI.” But then how do we determine who has and has not received this message? Is it through membership in the United Nations? Iran is a member nation, but many would argue Iran has not received this message, perhaps now they have with Rouhani at the helm, but that has yet to be truly tested. Even though Iran is not a great power, it has powerful allies in China and Russia that, if brazen enough, could stand up to the United States in the scenario that the United States felt so threatened by Iran’s nuclear program that they ordered air strikes to take out all of Iran’s enrichment facilities.
I am afraid that another war is inevitable, even though it may not be nearly as deadly as WWII. The next great power war may be a cyber war. “That we have not seen a cyber-incident as shocking as Pearl Harbor or 9/11 is not a cogent justification for academics to neglect the topic.” How does a country prepare for this? It must maintain a strong offensive and defensive military capability. Luckily, the United States is over-prepared in this respect, but it could afford to scale back the size of its military to a more reasonable size when compared to China’s military, for example. Additionally, an increase in cyber warfare capabilities should be implemented to protect against the possible new frontier of great power war.
Lastly, despite my realist tendencies in tackling this question, I do believe maintaining membership in international institutions is important if the United States is committed to eliminating some war, but we would be foolish to subscribe to the idea that an institution can overpower all of the inherent realist patterns of behavior in international politics. Similarly, recognition of the fact that great power war is on the decline does not mean that great power wars are over. Whether it is another sixty-eight years or twenty years, another war will disturb the long peace as it has disturbed every other long peace in human history.
 Steven Pinker, The Better Angels of Our Nature: Why Violence Has Declined (New York: Viking, 2011), 190.
 Kenneth N. Waltz, “Structural Realism after the Cold War,” International Security 25, no. 1 (2000): 39.
 Bill Marsh and Matthew White, “Population Control, Marauder Style,” New York Times, November 6, 2011, http://www.nytimes.com/imagepages/2011/11/06/opinion/06atrocities_timeline.html
 I calculated this average by taking the number of years between the end of a conflict and the beginning of the next for the ten deadliest conflicts by percentage of humanity killed. If conflicts overlapped, then the gap was valued as 0 years.
 Kenneth N. Waltz, “Structural Realism after the Cold War,” International Security 25, no. 1 (2000): 39.
 Steven Pinker, The Better Angels of Our Nature: Why Violence Has Declined (New York: Viking, 2012), 194-95.
 John J. Mearsheimer, “The False Promise of International Institutions,” International Security 19, no. 3 (1994/95): 10.
 Christopher Layne, “The Unipolar Illusion: Why New Great Powers Will Rise,” International Security 17, no. 4 (1993): 11.
 Ibid., 12, 15.
 Ronald L. Tammen et al., Power Transitions: Strategies for the 21st Century (New York: Seven Bridges, 2000), 42.
 Ibid., 185.
 Robert O. Keohane and Lisa L. Martin, “The Promise of Institutionalist Theory,” International Security 20, no. 1 (1995): 41.
 John Mueller, “The Obsolescence of Major War,” Bulletin of Peace Proposals 21, no. 3 (1990): 321-328.
 Ibid., 322.
 Ibid., 324.
 Adam P. Liff, “Cyberwar: A New ‘Absolute Weapon’? The Proliferation of Cyberwarfare Capabilities and Interstate War,” The Journal of Strategic Studies 35, no. 3 (June 2012): 404.