Introduction

The Roman army of the Republic - like any other army - was first and foremost a fighting organization. Its prime purpose was to defeat the enemy in battle. To achieve this goal, a body of men was assigned various tasks and structured into units. The instruments that were used to perform their task on the battlefield included not only weapons and military equipment, but also tactical means that were based on training, discipline, and experience. Moreover, no army could stay in the field for long without a supporting organization. Structure, weaponry, tactics, and organization were determined by the need to perform the army’s prime function effectively. If not, the army would soon have ceased to exist. However, no army is solely shaped by its primary purpose. Armies function in a landscape and are part of society, which, if they do not exactly determine the army, at least set bounds to its shape and functioning. Ecological factors and the economic, social, and political features of society partly explain the characteristic features of an army. As Roman society changed, so did the army. Moreover, the geography and climate of the lands in which the armies operated shaped the way Roman wars were fought. In his Histories, for example, the second-century historian Polybius notes the tenaciousness with which the Romans and their opponents fought during the wars in Spain. Only the approach of winter, he says, could disrupt the continuous fighting (35.1). In short, wars were restrained by the ecological conditions of agriculture and transport, and by the economic, social, and political structures of the society of which the army was a significant part.

However, this is not to argue for some kind of ecological determinism, or for a one-sided emphasis on the ‘‘external’’ influences of politics and economics. Wars were of great importance to Rome, and the army was an integral part of society, if only because its social and political leaders functioned as its commanders and the citizenry of Rome and its allies manned the armies. Warfare was sufficiently important to influence and direct developments in society and politics. For one thing, society

Created the instruments and means that the army needed to defeat its enemies; the needs of war caused developments that altered the conditions in which the army operated. Developments concerning the army in republican Rome are thus to be understood against the interaction of both army and society. The increase in scale of Roman warfare necessitated the further development of a supporting organization. The ability to defeat the ecological factor remained small, however, because Rome never escaped the limitations of a pre-industrial society, with its very limited sources of energy. Nevertheless, during the course of its Republican wars Rome built up an organization that was at least partly capable of overcoming the limitations offered by agriculture, land, and climate in waging war. This development contributed significantly to Rome’s ability and willingness to engage in overseas wars, which ultimately led to expansion on an unprecedented scale. War was thus an important part of state formation during the Republic. At the end of the Republic, Rome was able to bring together and sustain huge numbers of men that fought such famous battles as Philippi (42) and Actium (31). The latter battle left it to Octavian (63 bc-ad 14), the future emperor Augustus, to solve the problems of military deployment on such a vast scale.