According to the author, the main purpose of this book is to explain the Civil War - its causes, course, and consequences, in both a domestic and international context. It does not deal in any detail with battles or strategy, so readers seeking conventional military history should look elsewhere. But it is concerned throughout with how war affected the physical and psychic lives of soldiers and civilians, and how it shaped the course of politics, society, and culture inside Spain but also beyond.

The Spanish Civil War was the first fought in Europe in which civilians became targets en masse, through bombing raids on big cities. The new photo-journalism that made Spain's the first "photogenic" war in history also transmitted searing images of the vast numbers of political refugees produced by the conflict. There had been mass population displacements during the  First World War, but none had Spain's visibility. The Civil War made a deep impression on those watching from other European  countries.  As is well known, Spain became the place where other powers tested the latest technologies of warfare.