A THEORY OF THE DIFFUSION
OF MILITARY POWER
WAR is a harsh teacher, Thucydides tells us. We either learn from others who are better at fighting than we are or we die. Yet there are puzzles. France knew after World War I that Germany remained economically and demographically stronger than France. Knowledge of the emergence of blitzkrieg warfare in Germany was available. In the 1930s, however, the French Army planned for the same kind of slow, methodical, defensive war that World War I had taught, even though the logic of its alliance system called for an offensive against Germany in the event of a German attack on Poland. Why? Egypt suffered a massive defeat in 1956 at the hands of the Israelis. It received massive financial and military technological assistance from the Soviet Union. It had every incentive to beat the Israelis at their own game, and the material means to do so. But it suffered a massive defeat again in 1967, for exactly the same reasons. France and Egypt should have learned from those countries that most threatened them, yet they did not. Why?
Scholars interested in military power have devoted serious attention to the question of how states try to gain advantages over other states through the creation of new ways of generating military power, also called military innovations. Barry Posen (1984) and Stephen P. Rosen (1991) have theorized about the conditions in which militaries are most likely to innovate, disagreeing about whether innovations happen as the result of pressure from actors outside military organizations, military mavericks within the system, or changing promotion patterns that empower those with innovative ideas.1 This prior theorizing about military innovations in international politics, though, relies on clear implicit ideas about the way military power diffuses. By making those ideas explicit and engaging in empirical testing to determine which of them more accurately depicts world politics, this book explains how change in the international security environment occurs, advancing our understanding of military innovations beyond the first stage of the innovation life cycle.
Since we care about military innovations because of their consequences for international politics, it is necessary to focus on what happens after the initial innovation is demonstrated, not just on the innovation process. For example, blitzkrieg is more than an interesting historical footnote precisely because
1 For a recent review article, see Grissom 2006. For examples of some key works on military
innovation, see Avant 1994; Evangelista 1988; Kier 1997; Mahnken 2002; Pierce 2004; Posen
1984; Rosen 1991; Sapolsky 1972; Zisk 1993.
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