4 THE ROMAN EMPIRE
shot holes in the traditional system. Although subject to recurrent illness (he
nearly died in 23 BC ), Augustus served as Princeps for almost 41 years from
27 BC to AD 14, having already held power, with others or alone, for 16
years. No other emperor until Theodosius II (408–450) ruled for so long.
This, and the fact that he founded a dynasty, gave the new regime a strong
start.
Augustus’ interest in, or obsession with, the succession emerges as early
as 24 BC , no doubt stimulated by his own ill- health, though he never intended
his headship of the state to begin and end with him. In subscribing to the
dynastic principle, he was following the example of the Republican nobility,
but there was now much more at stake: the continued hold of a family on
power, the consolidation of a new system of government and the stability of
the commonwealth. There was, however, a fatal fl aw in rule by dynasty, at
least in the manner in which it developed in ancient Rome. Where the main
qualifi cation for selecting a successor was kinship or marriage connection
with the reigning family, sooner or later a weak, unpopular or tyrannical
ruler would arrive and in due course be removed with violence. The cycle of
anarchy, civil war, usurpation, and the foundation of a new dynasty would
begin again.
Nevertheless, the dynastic principle was seen from the start as a necessary
feature of the Principate, and not only by the emperor himself. Loyalty to
the imperial house was fostered and manifested early on among the military,
both the frontier legions and the praetorian guard (the emperor’s bodyguard),
and among the provincial elite and the people of Rome. The senate, over
whose membership Augustus now exercised a controlling infl uence, fell into
line, cooperating in the conferral of powers and offi ces on individuals within
the domus Augusta who were involved in the emperor’s plans for the
succession – just as the senate gave the emperor himself titles, powers and
honours. It became standard practice for a designated successor to be voted
powers held by the emperor himself, of which the most crucial were
proconsular imperium and tribunician power. Imperium was the power
invested in the higher magistrates, encompassing above all the authority to
command an army. Tribunes historically had the special function of
protecting citizens from arbitrary action by a magistrate, and were held to
be sacrosanct. They could both introduce laws (plebiscites) to the plebeian
assembly and veto the laws or resolutions emanating from magistrates or
the senate.^1
Every emperor aspired to have a natural son as heir, but under the
Principate few had sons who outlived their fathers, or sons at all, and fewer
still had sons who were successful emperors.^2 The fall- back solution was
adoption, preferably a family member, best of all a blood relative of the
emperor, if one was available.
Augustus, lacking a son, looked to his daughter Julia to give him
grandsons. Her sequence of husbands, Marcellus (nephew of Augustus),
Agrippa (general and friend), and fi nally Tiberius (stepson of Augustus),