This dissertation examines the combat motivations of the Roman legions during the late Republic and early Principate. It takes as the primary corpus of evidence the literary accounts of soldiers in battle from Sallust, Caesar, Tacitus, and Josephus in combination with epigraphic evidence from soldier’s funerary monuments. Evidence from these sources is evaluated in conversation with frameworks developed from observation of contemporary military behavior, predominantly those related to cohesion and sensemaking. I argue that combat motivation in the Roman legions can be organized into a scheme that privileges sensemaking as the dominant determinant of high or low motivation in most contexts but nevertheless retains a tension between a matrix of collaborative and competitive motivations.This dissertation is organized into four chapters. The first chapter aims to privilege the Roman, rather than contemporary, perspective on combat through a quantitative and qualitative analysis of vocabulary usage in these four authors. It argues that the Romans largely thought about combat in terms of virtus, innately Roman and public military prowess, and animus, the collective enthusiasm for battle amongst a fighting force. The second chapter examines the evidence from the epitaphs of soldiers’ funerary monuments and argues that these inscriptions exhibit a tension between collaboration, as represented by group affiliations, and competition, as represented by receipt of awards. The third and fourth chapters examine the Republican and Imperial narratives, respectively, and argue that these narratives demonstrate a strong connection between combat motivation and preparedness, which I argue is suggests sensemaking as an explanatory paradigm. I further argue that the tension between collaboration and competition is present in these textual narratives and its manifestation is dependent upon the sensemaking status of the soldier or collective force.