​Vasquez, John (2018) Contagion and War: Lessons from the First World War. Cambridge: Cambridge University Press. 401 pp.

​ISBN: 978-1-108-26116-6

Scott Wolford

University of Texas at Austin

Read more about this book: www.cambridge.org

​John Vasquez's Contagion and War leverages one of IR's dominant cases (World War I) to ask one of its most important questions: why do wars expand? The text surveys every dyad that saw at least one party declare war, describing relations in terms of alliances, territorial claims, rivalries, and previous militarized disputes. Vasquez also shows that other factors under-appreciated by quantitative IR, including the breakdown of prewar political order and imperial-hierarchical dependencies, further illuminate how a regicide in the Hapsburg periphery spawned a globe-spanning war. It's an important exercise in the logic of discovery, identifying a new set of facts for which future theoretical developments must account. If it suffers, it does so because of an exclusively 'steps-to-war' theoretical lens. Rising Serbian power, for example, gets cursory attention, yet those very gains in size, population, and capacity for nationalist agitation helped rationalize the Dual Monarchy's preventive war. Further, the argument that Belgium's decision to fight Germany is in 'direct contradiction to the bargaining theory of war' (p 318) relies on premises that (a) power wasn't shifting between the two and (b) German promises of restitution were credible. Yet bargaining theory would note that, once Germany was in control of Belgian territory, power would shift further in Germany's favor such that it could easily renege – thereby rationalizing Belgium's resistance. But these are minor issues. Most importantly, Contagion and War challenges Stuart Bremer's conjecture that war's outbreak and expansion have different causes: the empirical referents may differ, but the underlying causal processes that prompted the first and the last states to join the First World War are strikingly, tragically similar.