vernment from the time of the Gracchi was the policing of Rome
and the suppression of mob violence. To a certain extent the establishment
of the praetorian guard served to overawe the city mob, although only
three of its cohorts were at first stationed in the city. As a supplement
to the praetorians Augustus organized three urban cohorts, each originally
1500 strong, who ranked between the legionaries and praetorians. Between
12 and 7 B. C. the city was divided for administrative purposes into
fourteen regions, subdivided into 265 _vici_ or wards. Each region was put
in charge of a tribune or aedile. A force of six hundred slaves under the
two curule aediles was formed as a fire brigade. But as these proved
ineffective in 6 A. D. Augustus created a corps of _vigiles_ to serve as a
fire brigade and night watch. This corps consisted of seven cohorts, one
for every two regions, and was under the command of an equestrian prefect
of the watch (_praefectus vigilum_).

*The Annona.* Another vital problem was the provision of an adequate
supply of grain for the city. A famine in 22 B. C. produced so serious a
situation that the Senate was forced to call upon Augustus to assume the
responsibility for this branch of the administration. At first he tried to
meet the situation through the appointment of curators of senatorial rank,
but after 6 A. D. he created the office of prefect of the grain supply,
filled by an equestrian appointee of the princeps. His duty was to see
that there was an adequate supply of grain on hand for the market at a
reasonable price and in addition to make the monthly distribution of free
grain to the city plebs. The number of recipients of this benefit was
fixed at 200,000.

In this way Augustus was forced to take over one of the spheres of the
government which he had intended should remain under the direction of the
Senate and to witness himself the first step towards the breakdown of the
administrative dyarchy which he had created.

VII. THE PROBLEM OF THE SUCCESSION

*The policy of Augustus.* In theory the position of the princeps was that
of a magistrate who derived his powers from the Senate and the Roman
people, and hence the choice of his successor legally lay in their hands.
However, Augustus realized that to leave the field open to rival
candidates would inevitably lead to a recrudescence of civil war.
Therefore he determined to designate his own successor and to make