Yugoslavia, Rwanda, Liberia, Somalia, Azerbaijan, El Salvador, Northern Ireland, Lebanon, Cambodia -- all provide bloody evidence that civil wars continue to have a powerful impact on the international scene. Because they tear at the very fabric of a society and pit countryman against countryman, civil wars are often the most brutal and difficult to extinguish -- witness the American Revolution.
And yet, civil wars do inevitably end. England is no longer criss-crossed by warring armies representing York and Lancaster or King and Parliament. The French no longer kill one another over...