The task of a successor would not be easy, for there were many who would want to revert to the old system. Augustus was convinced that a reversion to the ‘bad old days’ would lead to chaos and that a single long-term Emperor was needed. The obvious solution was to appoint his boyhood friend Agrippa as his successor: he was a brilliant general who had the backing of the Army to put down any possible revolt – and who was also a brilliant administrator, second only to Augustus himself.
Unfortunately however he died in 12 BC and this left Augustus with a big problem. The easiest solution — and indeed the normal solution was to look to members of his own family (It only seems strange to us because we are so strongly opposed to nepotism. Yet this has been the norm in virtually all societies throughout the ages: it is the beliefs of the 21st century that are out of step). The trouble was that he only had one child, his daughter Julia by his first marriage, so he married her off to Agrippa. They had five children so his first choice was to look to his two grandsons, Gaius and Lucius. However fate struck again, for both died young, Lucius in AD 2 at the age of 19, and his elder brother Gaius 18 months later at the age of 24.
So he had to look yet again and he looked at his two stepsons. Livia, his second wife already had two sons by her first husband. One was Drusus who was clearly very bright, and the other was the dour but capable Tiberius. However Drusus died in 9 BC at the age of 29, so he was left, somewhat reluctantly with Tiberius, who eventually succeeded him: he proved to be a wise choice, for it was Tiberius who took over on Augustus’s death with dour competence and effectively confirmed the concept of the Roman Empire.
Augustus’s methods – keep the choice within the family, but then define the family widely, and adopt as successor whoever seemed the most competent – were often adopted by his successors, and in the second century, the great line of Emperors, Trajan, Hadrian, Antoninus Pius and Marcus Aurelius, were all adopted, and it was only when Marcus Aurelius was succeeded by his son, the neurotic Commodus, that the Golden Age of the Roman empire was broken. One wonders whether a similar system might not work with the British Royal family.