The Roman Army during the Pax Romana (27 BCE – 180 CE) was a highly organized and professional military force that played a central role in maintaining the stability and expansion of the Roman Empire. This period, known as the "Roman Peace," marked an era of relative tranquility and prosperity across the empire, facilitated by the army's ability to deter external threats, suppress internal revolts, and enforce Roman authority in its vast provinces. The army was structured into legions, auxiliary units, and naval forces, with soldiers drawn from both Roman citizens and non-citizens.
Under reforms initiated by Augustus, the Roman military became a standing army, featuring standardized recruitment, training, and equipment, along with fixed terms of service and regular pay. The legions, composed of heavy infantry, were the backbone of the army, while auxiliary units provided specialized roles, such as cavalry, archers, and engineers. These forces not only secured the empire's frontiers but also contributed to infrastructure development, such as building roads, bridges, and fortifications, which facilitated economic growth and cultural integration.