Michael Koortbojian's work examines the ways that the relationship between commanders and the city of Rome ‘was subject to continuous reinterpretations in a tradition that held sway for nearly a millenium’ (6). This is a significant matter, for the ways in which Romans envisioned the place of their city within their larger sphere of activity provided a central element of their polity as a spatial order. The beginning of the study's thousand-year tradition occupies an important place in the work. The author is especially concerned with tales of Rome's foundation that involved the creation of the pomerium, the boundary between the city and the surrounding world. Since these foundation stories also tied the pomerium to the city's original fortifications, the pomerium also excluded war from the city. The author, it should be noted, assumes that these narratives had some foundation in fact. In this way, the division into the spheres domi (‘at home’) and militiae (‘on campaign’) best represented the realities of archaic Rome, while subsequent activities that appear to complicate this sharp dichotomy between spaces of peace and of war appear as modifications of an earlier ideal that no longer matched reality.

Four chapters carry the investigation from Julius Caesar to Constantine, who provides the terminal date of the tradition's millennium. Each focuses on a set of images that, when viewed properly, bring into clearer focus new positions and practices. Three are at the centre of the first chapter, ‘Crossing the Pomerium: the Armed Ruler at Rome’: Pliny's report (HN 34.18) of a cuirassed statue of Julius Caesar in the forum; the Augustus of Prima Porta, another cuirassed statue; and Tacitus’ description (Hist. 2.89) of Vitellius’ arrival in Rome in a.d. 69 in which the commander changed from military to civilian attire and then entered the city with his troops. For the author, these images and actions provided clear statements that Caesar, Augustus, and Vitellius intended to retain their military powers when in the city. In other words, each was intended to make a claim to particular powers within the polity.

The second chapter, ‘Octavian's Imperium Auspiciumque in 43 b.c. and Their Late Republican Context’, emphasises an equestrian statue of Octavian that according to Velleius Paterculus (2.61.3) was placed at the rostra after the victory at Mutina in 43; it would soon be displayed on his coinage. Since he was a private citizen when given his command, his powers would only have been valid outside the city. Although he admits the evidence to be ambiguous, the author suggests that the statue should be seen against ‘the bellicose reality of the march on Rome that immediately followed its appearance’ (75) — that is, that it announced Octavian's intention to exercise his powers in the city, despite the restrictions of the original grant.

The third chapter, ‘Roman Sacrifice and the Ritus Militaris’, focuses on the imagery of sacrifice on the columns of Trajan and Marcus Aurelius. In public cult, celebrants following the ritus Romanus performed with their heads covered, while those employing the ritus Graecus did so with heads uncovered. On the two columns, however, emperors appear in military garb while sacrificing with their heads uncovered. The author suggests that these images reveal an otherwise unattested ritus militaris which shaped cult in ‘the military realm’ while ritus Romanus did so ‘in the domain of Roman civic acts’ (89). He also reexamines monuments that appear to support or contradict this reconstruction, and in the process also argues that the distinction between civil and military was no longer spatial but had become functional — that is, one could perform civil acts in the midst of armies and military ones in Rome.

The fourth chapter, ‘Constantine's Arch and his Military Image at Rome’, examines the arch that was installed after the victory at the Milvian Bridge. On it, an emperor who arguably had not triumphed enters the city in military costume and with his soldiers, thus proclaiming that the distinction between domi and militiae was no longer valid. Furthermore, the arch was placed on Romulus’ supposed pomerium, showing it to be a living concept at the time. As a result, in what might be seen as the general conclusion of the study, the pomerium appears no longer to have had any practical significance, although it continued to influence the learned.

This summary obscures the complexity of the argument and the broad learning with which it is carried forward. The author regularly acknowledges that his images had precedents and that other interpretations have been put forward and remain possible. Still, his decision to emphasise a single observation — that military matters and representations of command were not always excluded from the city — risks making complicated matters appear too simple. The distinction between domi and militiae was an ideal, and as an ideal its relationship to practice would have been neither straightforward nor absolute. As the author acknowledges, dictators kept their full powers when in Rome, while commanders might enter with their armies in their triumphs. In addition, the city long contained memorials of earlier victories and of the commanders who had won them. During the republic, the pomerium served to define the powers of magistrates, but in no period for which reliable evidence survives did it exclude all references to war.