Michael Grant sums up the career of Augustus in the following way (History of Rome. New York: Scribner's, 1978. 256-60):
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By his reorganization of the entire machinery of civilian government, he had proved himself one of the most gifted administrators the world has ever seen and the most influential single figure in the entire history of Rome. The gigantic work of reform that he carried out in every branch of Italian and provincial life not only transformed the decaying republic into a new regime with many centuries of existence ahead of it, but also created a durable efficient Roman peace. It was this Pax Romana or Pax Augusta that insured the survival and eventual transmission of the classical heritage, Greek and Roman alike, and made possible the diffusion of Christianity, of which the founder, Jesus, was born during this reign.
The dilemma Caesar's career had posedits demonstration that whereas the empire needed one-man rule, the nobles would tolerate no such thinghad been miraculously solved by Augustus. He had two things on his side: the Roman people's utter weariness of civil war, and his own subtle mastery of publicity in a wide variety of forms. Although, therefore, in every respect that mattered he was scarcely less an autocrat than Caesar had been, he contrived to cloak his absolutism in guises that looked old-fashioned enough to pass muster. . . . The conventional view of his character, in ancient times, differentiated between his cruelty in his youthful years and his mildness when he was older. But there was not so much need or occasion for cruelty in his later career as there had been earlier on; and when, even towards the end of his days, harsh measures were needed (for example, in the suppression of alleged conspiracies), he often remained ready enough to apply them. But nothing short of this degree of political toughness could ever have produced such vast results.
His domestic life, too, though simple and homespun, was conducted on ruthless lines. . . . When his daughter Julia and granddaughter of the same name moved in immoral smart circles suspected of subversion, he exiled them one after another, without compunction, and his third grandson, too, suffered banishment and perhaps violent death as well. And as for his male relatives who acted as his principal helpers, he was loyal to them but drove them as fiercely hard as he drove himself. He needed them because the burden was so heavy, and he especially needed the exceptional talents of Agrippa and Tiberius in the military sphere because, unlike most famous Romans before him, he himself was not a particularly effective general or admiral.