Any act of battlefield violence results from a combination of organizational strategy and a combatant's personal motives. To measure the relative contribution of each, our research design leverages the predictable effect of ambient temperature on human aggression. Using fine-grained data collected by US forces during the Afghanistan and Iraq conflicts, we test whether temperature and violence are linked for attacks that can be initiated by individual combatants, but not for those requiring organizational coordination. To distinguish alternative explanations involving temperature effects on target movements, we examine situations where targets are stationary. We find that when individual combatants have discretion over the initiation of violence, ambient temperature does shape battlefield outcomes. There is no such effect when organizational coordination is necessary. We also find that ambient temperature affects combat-age males’ endorsement of insurgent violence in a survey taken during the conflict in Iraq. Our findings caution against attributing strategic causes to violence and encourage research into how strategic and individual-level motivations interact in conflict.

任何战场暴力行为都是组织战略和战斗人员个人动机共同作用的结果。为了衡量每个人的相对贡献，我们的研究设计利用了环境温度对人类攻击性的可预测影响。我们使用美军在阿富汗和伊拉克冲突期间收集的细粒度数据，测试温度和暴力是否与可由个别战斗人员发起的攻击有关，但与那些需要组织协调的攻击无关。为了区分涉及温度对目标运动影响的替代解释，我们检查了目标静止的情况。我们发现，当个别战斗人员对暴力的发起拥有自由裁量权时，环境温度确实会影响战场结果。当需要组织协调时，则没有这种效果。在伊拉克冲突期间进行的一项调查中，我们还发现环境温度会影响战斗年龄男性对叛乱暴力的认可。我们的研究结果告诫不要将战略原因归因于暴力，并鼓励研究战略和个人层面的动机如何在冲突中相互作用。