The reign of Augustus initiated an era of relative peace known as the Pax Romana. The Roman world was largely free from large-scale conflict for more than two centuries,
Augustus restored the outward façade of the free Republic, with governmental power vested in the Roman Senate, the executive magistrates, and the legislative assemblies. In reality, however, he retained his autocratic power—with the Senate granting him lifetime powers of supreme military command, tribune, and censor. Augustus rejected monarchical titles, and instead called himself Princeps Civitatis ("First Citizen").
Beyond the frontiers, he secured the Empire with a buffer region of client states and made peace with the Parthian Empire through diplomacy. He reformed the Roman system of taxation, developed networks of roads with an official courier system, established a standing army, established the Praetorian Guard, created official police and fire-fighting services for Rome, and rebuilt much of the city during his reign.