In most cases wars are initiated by governments, not by populations. And, most of the time, they are the result of disputes over resources and land, or of a government's desire to increase its influence and power.

Why do humans start wars?

A major motivation of warfare is the desire of one group of human beings—usually governments, but often the general population of a country, tribe or ethnic group—to increase their power and wealth. The group tries to do this by conquering and subjugating other groups, and by seizing their territory and resources.

What is common cause of wars?

Major root causes include political, economic, and social inequalities; extreme poverty; economic stagnation; poor government services; high unemployment; environmental degradation; and individual (economic) incentives to fight.