Why do people wage wars?
War has always been a part of human history. Sometimes it’s small, involving only a few people. Other times, it covers entire regions and lasts for years. But when did the first war happen?
To understand that, we need to define what war is. According to one dictionary, war is an open and declared armed conflict between countries or states. This means real wars only began once humans settled into organized societies and formed nations. Before that, people lived in small, nomadic tribes. Once farming was invented, humans could live in one place, build communities, and collect resources. These resources sometimes attracted others who wanted to take them, leading to the earliest forms of war.
The earliest known war dates to around 2700 BC, when the Sumerians (in present-day Iraq) fought their neighbours, the Elamites (in present-day Iran). The Sumerian king led a successful attack, taking resources from the Elamites. This suggests early wars often started over fear of threats and the desire for resources.
For war to happen, groups must see themselves as separate from others—an “us vs. them” mindset. This division creates the chance for conflict. Wars often begin when one group feels threatened or wants what another group has.
There are different ways people study war. Some focus on history, politics, psychology, or economics. War is a very complex issue, so no single explanation is enough. Theories about war generally fall into two categories: one sees war as part of human nature, the other blames it on how societies and international systems are organized.
Some believe humans are naturally aggressive or that leaders act on false beliefs and fear. These psychological factors may lead to war. Others think that if people were better educated or emotionally balanced, wars could be avoided. Still, people’s behaviour changes based on the society they live in, so social structures matter too.
Some thinkers believe fear and mistrust between nations is the main cause of war, and suggest building trust to avoid conflict. Others suggest putting limits on what states can do to prevent escalation. Conflicts can grow quickly, just like when two countries start with trade disputes and end up in a trade war or arms race. But these don’t always lead to real war—sometimes, countries find ways to hold back. Understanding these limits and how to strengthen them is a big part of war theory.
Because wars are harmful, it’s in a country’s interest to find better ways to handle conflict. Some suggest that countries should act more rationally, understand their international environment better, and think more carefully about the costs of war.
In the 1800s, from 1815 to 1914, Europe saw fewer wars, partly due to a balance-of-power system. Countries worked to keep each other in check, avoided getting too strong, and made alliances to keep peace. Slow technological change and common cultural values also helped keep things stable during that time.
Today, a branch of mathematics called game theory helps us understand conflict. It looks at how decisions in competition are made. In some cases, when one country gains, another must lose (a zero-sum game). But even then, both sides can agree on a fair outcome. In other cases (non-zero-sum games), both sides can benefit if they cooperate. Understanding this can help countries avoid war by finding ways to work together for mutual benefit.