David Keen, Professor of Complex Emergencies at the LSE, tries in Useful Enemies to challenge the traditional, ‘common sense’ model of war as a contest between two (or more) ‘sides’ aiming to win. To make this challenge, he examines those various ‘functions’ of war served by strategies that aren’t aimed at gaining military victory: economic, political and psychological. In this way, he is seeking to demonstrate that wars are often fought and prolonged for reasons other than one side gaining victory over the other.

Thus, for example, we learn that in Sierra Leone in the 1990s, it suited all sides to prolong the conflict there because it gave all of them – government forces, rebels of the Revolutionary United Front (RUF) and peacekeepers from West Africa – the opportunity to enrich themselves through control