A few kilometres outside the Hungarian capital, Budapest, archaeologists made a remarkable discovery. In a grave from the sixth century BCE they found the remains of a Scythian woman and young boy. They were not rich. Still, their relatives had dressed them in fine clothes and laid them to rest in a tender embrace. Mother and son were victims of war, one of the many conflicts that the Scythian tribes fought with each other. Staring at them, I started wondering. How was it possible that these people could show so much love and care for their kin, yet repeatedly stumble from one bout of carnage to another? How is it possible today for countries to continue to arm themselves to the teeth, for wars still to tear apart so many loving families, and for diplomacy to fail so miserably to prevent military rivalry? Why has a planet that has always yearned for peace never managed to preserve it?

Peace and war, the famous American statesman Henry Kissinger noted, are the core business of world politics. Even if the international agenda has been broadened by environmental issues and matters as trivial as the curve of bananas, it is still diplomacy that bears an enormous responsibility when situations of great peril arise. This explains why diplomacy has remained such a weighty business, mystical almost, dignified by protocol and shrouded in secrecy. It also explains why young people remain attracted to it. Each year, numerous graduates compete in demanding entrance exams all over the world to join the corps diplomatique. Many more seek to be involved in international politics from the sidelines. I have written this book mostly for them, for the men and women that aspire to study, report or shape world politics, whether as politicians, diplomats, military officers, professors, or journalists.

World politics is again poised precariously at a tipping point. At one end of the balance sits a large crowd of cosmopolitans, the airborne elite that hops from one city to another and considers the success of diplomacy to be measured by the number of dialogues established or the flocks of cameramen present at international conferences. It insists that the bloody history of great power politics has ended and that major wars have become much less likely. Competition, such reasoning continues, is much less likely to spark major wars because of economic interdependence. This opinion was particularly dominant in politics after the collapse of the Soviet Union in 1991: in Europe, which has aspired to lead by example rather than by force; in China, which has designed the doctrine of peaceful rise; and in the United States of America, where conservatives and progressives alike have championed a foreign policy premised on liberal values.

At the other end sit the many who believe that the free and open world has not benefited them, that globalization is responsible for economic turbulence, and that both migrants and multinationals are a threat. They are angry and rally around strong nationalistic leaders. They want to be protected against a world of injustice and insecurity. As the cosmopolitans went on to revel in their flat, borderless world, this group has grown bigger and now severely limits the scope for international compromise and moderation.

This shift comes at a moment when the global levels of military spending are once again higher than during the darkest hours of the Cold War.1 The number of armed conflicts is also growing and other international disputes have become tenser. It is in this confusing world that a new generation has to chart its way and develop the wisdom to make the important decisions that face it. These leaders of tomorrow should be guided by good understanding of the people’s wellbeing, of economics, of ethics – and of history. As the ancient Roman statesman Marcus Tullius Cicero put it: ‘To be ignorant of what occurred before you were born is to remain always a child.’²

If theory and ideology give you a vantage point on the world much like that gained from a helicopter ride, history brings you to the same point only after a long and arduous mountain expedition. A journey through history strengthens the mind in the same way that an expedition in nature hardens body and soul. It requires perseverance and concentration to interpret the many events along the way. It develops the perceptiveness and awareness that are needed to detect and overcome hurdles. And it ultimately leads to great heights, from where one can look back, draw conclusions, and search for the best possible route towards the horizon ahead.

There is no shortcut for this voyage. However much we trust in the rigour of theory and the clarity of ideology, if we do not accept the challenge of coming to grips with history, it is like claiming to be religious without having read any sacred texts. Compared to ideology, history can be a moderating force. It reveals not only how much progress the world has made in improving living conditions, but also how hard-fought such progress – and its preservation – has been. From this perspective, world history can be viewed as an upward curve; but it has experienced dramatic setbacks along the way, which need to be understood in order to help prevent – or at least ameliorate – new crises in the future.

However, the study of history has increasingly become marginalized in the programmes of schools and universities. What remains often summarizes history in support of theories or preconceived ideas. In courses of international politics, for example, history is at best limited to the same handful of case studies, like the Peloponnesian War, the rise of ancient Rome, or the workings of the nineteenth-century Congress System.3 It instantly becomes clear that the subjects that are always focused on relate to only a small area of the globe: Europe. This has led scholars outside Europe to claim that the strategic culture of their own countries is fundamentally different and stands apart from vicious European power politics. I have heard this argument many times: from Chinese colleagues and diplomats who refer to an alleged tradition of harmoniousness innate to the Middle Kingdom; or from Indian officials who consider their nation to have been founded on Gandhi’s principles of peace. Such geographical limitations in the study of history inevitably cause misunderstanding and disagreement.

Writing History

So, what should readers expect from this book? In order to answer that question, I should first explain what this book is not. It is not a specialized work that reveals new discoveries from archaeological sites or archives. It does sometimes draw upon primary sources, but it also gratefully relies on numerous excellent secondary sources. Nor is this book another history promoting a single great idea: that there is a ‘clash of civilizations’ brewing, for instance; or that we are nearing ‘the end of history’; or that humans have always been rational optimists who advanced their prosperity through trade. Neither is this a work of historical revisionism that tries to provoke controversy by attacking earlier studies. To be sure, like any other student of international affairs I do have predispositions, but I have not set out merely to confirm them. In fact, I did not know what to expect when I embarked on the research for this book, as much of what I had to explore was new to me.

In writing this book, I have been guided by a single question. What do I want the shapers of this world to know about the history of world politics, given that they have so many other issues to engage with, so many other courses to take? The result is a bird’s-eye view of 3,000 years of history: an introduction that acquaints the reader with essential events, allows him or her to draw some conclusions about the functioning of international relations, and hopefully awakens enough interest in some aspects that they go on to explore them in greater detail themselves. It can be used by students at university, but equally by any reader with a desire to make sense of our restless world, to understand where we come from, and to gain some idea of what the future might bring.

To that end, this book integrates different aspects of history that are usually treated separately. There are magnificent works about the causes of war, but they do not dwell on periods of peace.4 There are masterful studies of the historic shifts in the balance of power, but they overlook much of the way international politics has been conducted:⁵ how international organizations have been founded, how treaties have been negotiated both in cramped back rooms and in marble ballrooms, how the personal beliefs of participants have played significant roles, and how diplomats have shaped the rules of world politics. My challenge has been to unpack these different but interrelated layers into one consistent enquiry.

The first of these layers concerns the history of the distribution of power across the globe from the earliest times onwards. Power, as the political scientist Robert Dahl put it, is the ability to make people do what they otherwise would not have done.⁶ For a polity or state this has both an internal dimension – that is, its influence over its citizens – and also an external one – that is, its influence over other polities. Power, in these terms, has two aspects: its inputs, or capabilities, and its outputs, or effective influence. This effective influence can be both hard and soft. It can involve everything between forceful subjugation and subtle inducement – with diplomacy merely the art of mediating between one’s own country’s domestic interests and those of others.

When we focus on inputs, a polity’s capabilities can be measured in terms of its land and natural resources, its treasure, its military power, its political system, its legitimacy as a state, and so forth. These are never static, but their relative distribution among polities shapes the balance of power at any one point in time. Many scholars study the processes by which polities accumulate and lose capabilities. One of the most critical areas of discussion in this regard concerns the ways social, economic, and political organization – as well as individual leadership – affect the accumulation and conservation of capabilities. Is Western capitalism really a superior form of economic organization? Is democracy necessary for prosperity, or do we need authoritarian leadership? Another important area of debate concerns the impact of ideas on the value of material assets. For example, why do polities appear to value military power differently at certain times? Do the wealthiest economic powers shape the way in which other states define their own needs?

This leads us to the second layer: the history of political organization. Polities have taken numerous different forms: cities, city states, nation states, multinational unions, and empires ranging from indirect trading ones to the directly territorial. They have been organized as monarchies or republics, dictatorships or democracies, and so on. And they have coexisted with other influential agents such as religious groupings, international corporations, and even pirates.

Until a few years ago, the predominant assumption was that we would live in an egalitarian, borderless world, and that states were about to become powerless. We observe a completely different reality today. Nationalism is back, people call for well-protected borders, military expenditure is on the rise, and governments interfere incessantly in economic affairs. The current debate about the importance of geographically delimited political power versus cosmopolitan trade, capital, ideas, and culture is by no means new. This book pays attention to the factors that historically have caused shifts between cosmopolitanism, fixated with openness, and protectionism, obsessed with borders and defence.

The third layer concerns the history of interaction between political units. Time and again, people have stood up to proclaim that the very nature of international relations was about to change for the better: competition would continue, but it would become less violent. Just as, in the fifth century BCE, the Athenian statesman Pericles promised other Greek cities peace and security if they joined his Delian League, so, twenty-five centuries later, the American president Harry Truman vowed to protect the free world, and, in the last few years, the Chinese president Xi Jinping has held up the vision of a harmonious new world order. But according to the great political scientist Hans Morgenthau, underneath the chaos of international politics there are perennial forces that shape all societies, such as humans’ limitless lust for power and the consequent rivalry between states.7 So, can we deduce any pattern in the occurrence of war and peace throughout history? What has made war more prevalent than peace? And what, on the contrary, has driven powerful agents to champion the cause of peace and tie themselves to conventions, to international organizations, and to rules restricting sovereignty? To what extent have international relations been driven by a desire for defensive security, or territorial aggrandizement, or economic profit, or by ideas of religion, nationalism, or justice, or simply by ignorance and folly? Do states become more restrained in the use of force and more keen to cooperate as a result of economic interdependence, increased communication, and shared values?

The fourth layer to consider is the history of the relationship between people and the planet; in other words, the importance of nature and environmental change. Some of the first writers about politics – such as the Indian court advisor Kautilya and the Chinese strategist Sun Tzu – were already advising leaders to husband their natural resources carefully. For much of history one of the principal tasks of monarchs has been to intercede with the gods for favourable weather. Climatic changes, food scarcity, and the migrations instigated by them have caused social upheaval and war at least since Egypt was first ruled by the pharaohs. So, in the twenty-first century, what is new in this regard? Should we consider global warming a new component of the international agenda? Or is it just as Kautilya and Sun Tzu wrote over two thousand years ago, that any leader who wants to be successful must strike a balance between the desires of his people and the resources of nature?

The fifth, and final, layer concerns thinking how the nature of world politics has evolved throughout history. After the fall of the Soviet Union, the debate was dominated by optimistic scholars, so-called liberals, who advocated that trade made polities more dependent on each other and that this interdependence made conflict more expensive, and so-called constructivists, who assumed that international norms dissuaded polities from using force against each other and that even their very DNA could be changed, away from a predisposition to selfish national interests and towards a greater focus on the common good. Within the last few years, however, politically realist intellectuals have become more audible. They believe that polities will always strive for autonomy, security, and power; as a result, cooperation and peace are unlikely to be sustainable. The world remains gripped by anarchy, which for students of international politics means the perpetual competition between polities and the absence of a durable force that can arbitrate or solve their disputes. This shift from optimist idealism to pessimist realism is nothing new, as this book will show. It will keep track of the two schools of thought as they alternate through history, and pay particular attention to the reasons why each viewpoint gained its momentary prominence and then declined in turn.

In total, this book surveys 3,000 years of history, from the beginning of the first millennium BCE to the beginning of the twenty-first century CE. Each chapter covers two to three centuries and concentrates on the geographical region that the historical evidence suggests at that time was most important: because of the size of its population, because of its strength, or because of its leadership in international affairs. This way, the focus will move from east to west, north to south, as it follows the ever-shifting centres of power. Inevitably, some regions will figure less prominently than others, like sub-Saharan Africa and the Americas. For most of their history they were less densely populated than other areas – until the nineteenth century they probably accounted between them for less than 10 per cent of the world’s population – and sources for their pre-colonial political organizations are also much scarcer. Nevertheless, this work does at least touch on polities like the ancient Olmec cities of Central America and the medieval kingdoms of Central Africa, as well as addressing the fate of other less prominent actors in world affairs: the wary countries on the fringes of big empires, the peoples enslaved during wars, and the shrewd trading cities that cautiously sought to hedge their bets between the political giants.

Throughout, the book takes a keen interest in the impact of world politics on the lives of ordinary people. Besides the effects of economic change, it was often the outbreak of war that had the greatest ramifications, and so we will attempt to trace the causes and consequences of conflicts, investigate how they were won and lost, analyse how they were perceived, as well as follow the diplomats in their desperate attempts to stop them. Even if our aim is to try and abstract timeless underlying themes from the history of war and peace, it must remain above all a story of human beings, of their hopes and fears, their capacity for violence and their suffering. That is the only way we will ever understand the hard choices that define the nature of true leadership.