Civil war

A civil war is a violent conflict occurring within the borders of a single country.

Unlike international wars fought between different nations, these battles occur between organized groups of citizens. These groups often fight to seize control of the central government or a specific region. They may also fight to force changes to existing government policies. While the fighting is internal, most modern civil wars involve intervention from outside powers. Research shows that about two-thirds of the 138 intrastate conflicts between 1945 and 2000 involved help from other countries.

Scholars use different rules to define exactly when a disturbance becomes a civil war. The intensity of the fighting is often a point of debate among political scientists. For example, some experts define a civil war as a conflict with more than 1,000 casualties. Others require that at least 100 casualties come from each participating side. The Correlates of War, a famous dataset used by researchers, uses a rate of 1,000 casualties per year. This specific rule means some famous struggles, like the conflict in Northern Ireland, are not included in their count.

Civil wars have changed significantly in duration and scale over time. Between 1900 and 1944, the average civil war lasted only one and a half years. Since 1945, that average has risen to just over four years. This increase in length means more wars are happening at the same time. In the first half of the 20th century, there were usually no more than five civil wars occurring simultaneously. By the end of the Cold War, that number rose to over 20 concurrent wars.

The human and economic costs of these conflicts are very high. Since 1945, civil wars have resulted in the deaths of over 25 million people. Millions more people have been forced to leave their homes and flee their countries. These wars can also cause a nation's economy to collapse entirely. Countries like Somalia, Burma, Uganda, and Angola once had promising futures. However, they were later engulfed in civil wars that damaged their development.

Researchers study three main explanations for why these wars begin: greed, grievance, and opportunity. Greed refers to individuals or groups trying to maximize their own profits. Grievance focuses on conflict caused by social or political injustice. Opportunity refers to factors that make it easier for people to organize violent movements. A major study by the World Bank used the Collier–Hoeffler Model to examine these causes. They analyzed data from 1960 to 1999 to see which factors truly predicted war.

The study found that economic factors are often more influential than social identity. For instance, a high dependence on exporting primary commodities increases the risk of conflict. A country where these goods make up 32% of its gross domestic product has a 22% risk of war. In contrast, a country with no primary commodity exports has only a 1% risk. This is likely because it is easier to capture a gold mine or an oil field than a factory. On the other hand, factors like higher male secondary school enrollment can reduce the chance of war. If young men are in school or have steady jobs, they have more to lose by joining a rebellion.

While identity can play a role, the data shows that certain social factors are less predictable than economic ones. For example, differences in religion or ethnic makeup do not always lead to war. However, ethnic dominance can be a risk factor. When one large ethnic group makes up the majority, the risk of civil war nearly doubles. Interestingly, the study found that having a diverse population of many different groups can actually decrease the chance of war, provided no single group dominates. This shows that the complex mix of money, power, and social structure determines how a nation stays at peace.