R. has had a long interest in military matters in imperial Rome (her earliest publication on the topic was in 1994), and this recent book on the security of the emperor fits well with her previous research. As the title suggests, the focus is on the ways in which the emperor maintained his security in the capital and in those regions in Italy that were frequented by the imperial family. R. makes it clear from the preamble that the purpose of the book is to consider the rationale and the means that allowed the princeps to take up ‘the role (and essentially implement the project) of guarantor of peace and safety of persons and of public places’; she then considers the ways in which such a plan was modified or adjusted over the two centuries after Augustus and examines how widely this plan extended in Italy.

There are four parts to the book. Part 1, ‘From Public Order to Security’, looks at previous scholarship and introduces what R. will focus on as a result of what she perceives to be a gap in the scholarship, namely considering to what extent there was a broad plan to prevent threats to security, both to the emperor himself and to the city at large from the very start of the imperial period. Part 2, ‘The Birth of a Dispositive’, looks at two broad areas: security of the emperor in Rome and security of the city and inhabitants. The use of the term dispositive, borrowed from Michel Foucault, is meant to be inclusive, allowing R. to consider elements ranging from the legal aspects to the built environment. This section thus begins with a survey of the legal framework, which is often overlooked in discussion of the security system established by Augustus early in his reign. R. then turns to the actual units in the city. Here the argument is less robust, sometimes without adequate support for what are controversial issues, such as the question of the relationship between the praetorian and urban cohorts in the earliest period of their existence. Part 3, ‘Testing a Dispositive’, consists of two sections, the first looking at the physical manifestation of security (for example, the Castra Praetoria) and then at places in Rome that were potential problem areas, such as baths and spectacles. The second part is on the urban cohorts; this is one of the most useful parts of the book, given R.'s update of H. Freis's book (Die cohortes urbanae [1967]) and the inclusion of recent epigraphic material. The final section, Part 4, ‘Policing and Security in Imperial Italy’, consists mainly of three case studies, all of which R. has published elsewhere, that examine the use of urban troops in Italy. An epilogue provides a good summary of the arguments presented.

The overarching thesis, that the security system as established by Augustus evolved over time and that changes were made in the ensuing years to ensure the stability of that system, may seem obvious, but R. is right to set it into the wider context of the legal framework and to consider issues outside of the capital. Yet the book is not without its problems. There is a tendency to accept the literary sources at face value and, in particular, to use the Digest to show practices in the early period. Much of the evidence adduced is quite late (Antonine and Severan). All of these combine to make the arguments for the early period less compelling. R. does not always note the controversies with issues concerning the urban units. For example, she glosses over the problems surrounding the creation of the frumentarii and their role; similarly, she does not consider the controversy over when the increase in the number of praetorian cohorts occurred. She also creates a rivalry between the urban and the praetorian units, which is not evidenced in the sources, and never considers the difference in pay for these units, which is a major consideration in determining status. Her claim that the Severan cashiering of the guard was the result of a long process in which the praetorians were sidelined is also not tenable: while there had been minor changes to the unit in the second century, that Severus cashiered the entire unit and replaced it with legionaries is the most significant change to the unit since its inception in 27 bc and so was ‘disruptive and shocking’, something that she denies.

One of the main challenges with this book, however, is the denseness of the prose. It is sometimes difficult to understand the argument without rereading sections. There was also a need for closer proofreading: spelling mistakes abound. There are some factual errors: Severus’ decennalia was in ad 202, not 204 (p. 56); there is mention of a securitas coin under Nero as a result of the Pisonian Conspiracy, but the coin shown is dated to ad 63 (p. 49); there is a reference to a pivotal date of ad 6 on p. 77, which later appears as 6 bc (p. 90); Alexander Severus was not Septimius’ grandson (p. 132); the castra praetoria was attacked in both 69 and 238 (p. 142); the date of the foundation of the guard by Augustus was not ad 6 (p. 231).

Despite these difficulties R. has provided a thought-provoking study of security in imperial Rome, and the broad approach offered means that there will be something of value for anyone interested in the city units and the ways in which the emperors managed to keep their immediate world secure – at least for the first two centuries of the principate.