Since neither Antony nor Octavian, nor indeed an alliance between them, was about to do the impossible and reestablish the defunct republic, Octavian’s prevailing challenge after his victory at Actium in 31 BC was to shape, almost imperceptibly, a one-man rule that would be acceptable to a population that had grown up innately fearful of monarchy.

As Octavian consolidated his position in this way, he emerges from Bleichen’s bold but detailed biography as rather a remote figure. Tellingly, he ceases to be elusive to us principally when he is unpleasant: “Octavian’s ethical standards were a good deal lower in affairs of the heart than those of most of his contemporaries and equals, and all his life he ruthlessly exploited his position of power to satisfy his sexual needs. He did not stop short at other men’s wives.”

After impregnating his wife Scribonia, Octavian fell passionately in love with the married Livia Drusilla, who was descended from the illustrious Claudii Pulchri family, and herself pregnant at the time with her husband’s child. Surprising though it may be, their marriage proved to be a strong one. Livia’s virtuous reputation to some degree made up for Augustus’ deficiencies, which was important because he liked to present himself as the redeemer of national morality.

Before he died, he wrote the Res Gestae, an immodest account of his own achievements, which included the reconstruction of many of Rome’s temples, and the introduction of laws to reinvigorate family life. One of these laws required the Roman people to marry and have children. Another — which remained in force until the third century AD — rendered adultery illegal.

While it is easy to point to Augustus’s hypocrisy, not least in his failure to have children by Livia, we are discouraged from doing so. The majority of Rome’s senators supported his legislation, Bleichen reminds us, as it professed to revive good old-fashioned morals. In its very willingness to agree to it, however, “society gave up a part of its freedom”. The people led themselves into the principate that Augustus was subtly establishing by combining the flavour of the old with the new.

Bleichen has acknowledged a debt here to the 19th-century historian Theodor Mommsen, whom he gushingly called “the foremost historian of the ancient world, and not only in his own time”. While Mommsen attracted criticism from fellow scholars for appearing to play down the monarchical nature of the principate by emphasising its continuity with the early republic, Bleichen has breathed new life into his argument. Augustus’s preoccupation with moral legislation helped him to make radical changes beneath a veil of tradition.

Look at almost any portrait bust of Augustus (there are no plates in this volume so one must look elsewhere) and you will be struck by his serenity. The smooth appearance of the man who believed in his own divinity and championed the Pax Romana, one starts to realise, isn’t mere whitewash.

The first emperor of Rome was perfectly capable, and certainly fixed in his ideas, but by comparison with Julius Caesar he was just a bit bland. Fortunately for Augustus, a bit of blandness wasn’t entirely uncalled for in Rome after the turmoil of the previous decades.

Augustus will always be remembered as the architect of empire, and it is no failure on Bleichen’s part that the architecture is more interesting than its draughtsman.