In his 2009 book War on Sacred Grounds (Ithaca, NY), Ron Hassner examined how sacred space generates Fearon-esque issue indivisibilities, inhibiting the bargaining for peaceful dispute resolution. He focused mainly on intra-state conflicts with overtly religious dimensions. Hassner's latest book, Religion on the Battlefield (Ithaca, 2016), represents his work's natural evolution. He widens the inquiry beyond the sacralization of space, adding time, persons, and rituals. He shifts the focus from nonstate actors in domestic/transnational conflict to state actors in interstate conflict. He examines religion's influence in conflicts in which belligerents’ primary goals are not overtly religious.

Hassner seeks to dispel, as he puts it, four “myths” (154). First, the myth that religion is a dichotomous variable, i.e. conflicts are either religious or secular. Second, that religion's role in the conflict is limited to promulgating ideas, i.e. religion influences only conflict causes, not outcomes. Third, that a religious sect's motivations and practices are predictable from its formal theology or scripture. Fourth, that religious ideas always influence combatants.

His modus operandi is to organize the elements of religion's effects into four ideal types, classified by the target (Self or Other) and religious environment (constraining or enabling), as shown in Table 1. In each case, the combination of target and environment results in religion acting as either a “force multiplier,” rendering one's own side more effective militarily thus raising the probability of victory, or a “force divider,” rendering one's side less effective thus raising the probability of defeat.

Table 1.

Ideal Types of Religion's Effects on Armed Conflict Outcomes

On its own terms, Hassner's typology seems sound and the extensive case studies appear to support his thesis well. But a major point of contention arises when this work is situated within the security studies literature. In that literature, the prevailing convention is that the two primary contributors to military victory are capability and resolve. Hassner chooses instead to use the terms “force multiplier” and its theoretical inverse, coined “force divider.”

Therein lies the disconnect. U.S. Department of Defense Joint Publication 3–05.1, Joint Special Operations Task Force Operations (April 26, 2007), defines “force multiplier” as “[a] capability that … significantly increases the combat potential of that force and thus enhances the probability of successful mission accomplishment” (emphasis added). For religion to affect capability is somewhat rare—usually consisting of religious fasting (lowering individual combatants’ physical strength) and religious assemblies and holidays (lengthening the time required to mobilize). Hassner does account for these things. However, the bulk of his case studies illustrate religion's multiple effects not on forces’ capabilities, but their resolve. He shows effectively how, for example, attacking on the attacker's religious holiday tends to motivate (enhancing the attacker's resolve) but attacking on the adversary's holiday tends to provoke (enhancing the target's resolve); and how military chaplains and use of prayer and religious charms tend to ease individuals' fears and raise their resolve to fight. The real story—and Hassner's real contribution in this book—is about religion's effect, both positive and negative, on resolve.

The book has several strengths, which I will briefly describe prior to discussing the limitations:

First, the book breaks new ground. The literature on religion as a cause of conflict is already extensive. The same is true for literature on religion's effects on domestic conflict. In contrast, Hassner mines veins that up to now have been virtually untapped: religion's influence on conflict outcomes and on the otherwise secular conflict between state actors. In doing so, Hassner makes important contributions to questions that have been understudied and undertheorized.

Second, the historical case studies are deeply documented, at least for those with widely available historical records (e.g. of the Allied Powers of World War II and transparent democracies today). Hassner himself expresses concern over selection bias potential due to overabundant case studies of Abrahamic religions (Christianity, Judaism, Islam). However, to paraphrase Mr. Rumsfeld, we go to war with the data we have, and the records that are available do amply supply illustrations of the effects Hassner seeks to tease out.

The last chapter is devoted entirely to the Iraq War (2003–2009), viewed primarily through the lens of U.S. forces. Hassner shows how sacred ideas were causal motivators of the sectarian civil war and how sacred time, space, leaders, and rituals had multiple effects. Particularly poignant is the chapter's exposé of an astounding level of local religious chauvinism in the double-standard attributing all moral responsibility for targeting or “desecrating” mosques to the United States, while absolving insurgents of their moral responsibility for militarizing mosques in the first place.

Third, the book displays Mearsheimerian honesty about the existence of counter-illustrations. For example, in the bombing campaign on Germany during World War II, the Allies mostly spared churches in Magdeburg, but not in Würzburg.

While the book has many strengths I do quibble with several elements of the analysis:

Going to Hassner's first so-called “myth”: Although it may be true that conflicts are not necessarily purely religious or secular, I submit that individual religions are reduceable to a dichotomous variable and that doing so can and does produce significant results. I grant that continuous variables are preferable, but even a dichotomous variable can uncover trends that case studies cannot.

Regarding his third “myth”: Hassner rightly points out that religions are not monolithic and adherents have wide ranges of opinions and practices. However, each religious denomination, even at the level of major world religion, is grounded in a basic package of ideas memorialized in scripture and other classical writings. Therefore, we should expect a majority of religionists to congregate around some median or modal norm.

Finally, Hassner's entire analysis is rooted in Martin Riesebrodt's limiting conception of religion as a collection of practices. This has led him to emphasize dimensions such as rituals and holidays, at the expense of examining how different religions have promulgated different logics of causation, appropriateness, and rectitude. Thus, while Hassner's treatment in Religion on the Battlefield fills important gaps, it leaves essential gaps for others to fill.