The height of Roman power coincided with the first two hundred years of the Roman Empire, a period that was remembered as the Pax Romana: the Roman Peace. It was possible during the period of the Roman Empire's height, from about 1 CE to 200 CE, to travel from the Atlantic coast of Spain or Morocco all the way to Mesopotamia using good roads and enjoying official protection from banditry and a common trade language. The Roman Empire was as rich, powerful, and glorious as any in history up to that point, but it also represented oppression and imperialism to slaves, poor commoners, and conquered peoples.
Octavian was unquestionably the architect of the Roman Empire. Unlike his great-uncle, Julius Caesar, Octavian eliminated all political rivals and set up a permanent hereditary emperorship. All the while, he claimed to be restoring not just peace and prosperity, but the Republic itself. Since the term Rex (king) would have been odious to his fellow Romans, Augustus instead referred to himself as Princeps Civitatus, meaning “first citizen.” He used the senate to maintain a facade of republican rule, instructing senators on the actions they were to take; a good example is that the senate “asked” him to remain consul for life, which he graciously accepted. By 23 BCE, he assumed the position of tribune for life, the position that allowed unlimited power in making or vetoing legislation. All soldiers swore personal oaths of loyalty to him, not the republic, and having conquered Egypt from his former ally Mark Antony, Augustus was worshiped there as the latest pharaoh. The senate awarded Octavian the honorific Augustus: “illustrious” or “semi-divine.” It is by that name, Augustus Caesar, that he is best remembered.
Despite his obvious personal power, Augustus found it useful to maintain the facade of the republic, along with republican values like thrift, honesty, bravery, and honor. He instituted strong moralistic laws that penalized (elite) young men who tried to avoid marriage and he celebrated the piety and loyalty of conservative married women. Even as he converted the government from a republic to a bureaucratic tool of his own will, he insisted on traditional republican beliefs and republican culture. This no doubt reflected his own conservative tastes, but it also eased the transition from republic to autocracy for the traditional Roman elites.
As Augustus’s powers grew, he received an altogether novel legal status, imperium majus, that was something like access to the extraordinary powers of a dictator under the Republic. Combined with his ongoing tribuneship and direct rule over the provinces in which most of the Roman army was garrisoned at the time, Augustus’s practical control of the Roman state was unchecked. As a whole, the legal categories used to explain and excuse the reality of Augustus’s vast powers worked well during his administration, but sometimes proved a major problem with later emperors because few were as competent as he had been. Subsequent emperors sometimes behaved as if the laws were truly irrelevant to their own conduct, and the formal relationship between emperor and law was never explicitly defined. Emperors who respected Roman laws and traditions won prestige and veneration for having done so, but there was never a formal legal challenge to imperial authority. Likewise, as the centuries went on and many emperors came to seize power through force, it was painfully apparent that the letter of the law was less important than the personal power of a given emperor in all too many cases.
This extraordinary power did not prompt resistance in large part because the practical reforms Augustus introduced were effective. He transformed the senate and equestrian class into a real civil service to manage the enormous empire. He eliminated tax farming and replaced it with taxation through salaried officials. He instituted a regular messenger service. His forces even attacked Ethiopia in retaliation for attacks on Egypt and he received ambassadors from India and Scythia (present-day Ukraine). In short, he oversaw the consolidation of Roman power itself after the decades of civil war and struggle that preceded his takeover, and the large majority of Romans and Roman subjects alike were content with the demise of the Republic because of the improved stability Augustus's reign represented. Only one major failure marred his rule: three legions (perhaps as many as 20,000 soldiers) were destroyed in a gigantic ambush in the forests of Germany in 9 CE, halting any attempt to expand Roman power past the Rhine and Danube rivers. Despite that disaster, after Augustus’s death the senate voted to deify him: like his great-uncle Julius, he was now to be worshipped as a god.