John A. Vasquez explains the processes that cause the spread of interstate war by looking at how contagion worked to bring countries into the First World War. Analysing all the key states that declared war, the book is comprised of three parts. Part I lays out six models of contagion: alliances, contiguity, territorial rivalry, opportunity, 'brute force', economic dependence. Part II then analyses in detail the decision making of every state that...