Originally published in 1938, this book consists of a group of papers considering widely different subjects, but all bearing upon one social problem - the causation and prevention of war. The authors all occupy the same general political position, they are democratic socialists and active members of the Labour Party. The book falls into three rough divisions, although all the papers are self-contained. The first part of the book is psychological and attempts to summarise and analyse the non-historical evidence (ecological, psychological, and anthropological) about the causes of fighting. The second part is historical. It surveys the different causes of international war in the nineteenth century and then discusses the relation between nationalism and capitalism during the same period. The third part is political and first considers the relation of the use of force to the preservation of peace. Then analyses the choices of foreign policy for a pacific power confronted by the threat of aggressive military dictatorship. It concludes with a review and assessment of the various available policies for the prevention of war in general and under the specific contemporary conditions of the time.