Thus the ageing Augustus boasted of having ‘compelled’ the Parthians to return the insignia of Crassus (among others). No true compulsion was involved in this transaction – or at least none of a military nature. The Roman–Parthian accommodation came through diplomacy and inaugurated a peace that lasted until renewed hostilities under the Julio-Claudians. Therefore, the language of the Res Gestae fittingly sets the stage for a discussion of S.'s wide-ranging treatment of Roman–Parthian relations. We encounter a forceful and persuasive argument that, from the very beginning, both parties found ways to do exactly what Augustus did: minimising bloodshed, while presenting their activities domestically in the guise of armed conflict. Leaders ‘often balanced two priorities: an avoidance of uncertain and costly war, and a simultaneous need for violent posturing and victory’ (p. 16).

While a preference for reaching foreign goals peacefully is unsurprising, S.'s departure from the communis opinio lies in his understanding of how the system broke down: most famously during the failed campaign of Crassus in 53 bce and then again with the eastern adventures of Trajan and later emperors. We see no ‘clash of civilisations’ locked in never-ending conflict nor any mercenary attempts to control trade routes (the foundational studies of N.C. Debevoise, Political History [1938] and M. Colledge, The Parthians [1967] still exert a dominant influence in these matters). For S. purely military explanations are also inadequate (P. Edwell, Between Rome and Persia [2008], and R. Sheldon, Rome's Wars in Parthia [2010], provide recent examples). The work stands in contrast, too, to the idea that ancient international relations were a zero-sum game in which Realpolitik dominated and armed conflict was inevitable (see N. Overtoom, Reign of Arrows [2020], which deals only with the first phases of Parthian expansion). When they fought, S. sees Romans and Parthians responding to expectations created by the warlike rhetoric that accompanied earlier diplomatic settlements (although most of the attention is on the Romans, we see indications that Arsacid leaders faced similar constraints).

The tone is revisionist. After laying out the majority opinion on key issues, S. proceeds chronologically, starting with the mid-90s bce. Although Mithridates II executed his representative for meeting with Sulla and Ariobarzanes of Cappadocia as equals, he did not reject an agreement with the Romans (whether it was a foedus or a more informal relationship is left unresolved). After all, it was the Parthians who, according to Plutarch, had inquired seeking συμμαχίας καὶ φιλίας (Plut. Sull. 5.4). At every stage S. points out that belligerent posturing overlaid (and sometimes came in service of) attempts to achieve a workable settlement.

Pompey's years in the East are a microcosm of S.'s approach. Again he finds reasons to downplay the level of hostility. By adjusting the translation of περισκοποῦντα (Cassius Dio 36.51) S. reinterprets the Parthian Phraates’ invasion of Armenia in 66 bce to keep him from violating an undertaking with Pompey: acceptable, perhaps, for the sake of argument; but readers may balk at attempts to minimise the creation of new eastern provinces. Defence against the Parthians is the prevailing explanation for such measures, in Pompey's time and later, but there is always another possibility, and S. is adept at finding the alternatives.

This is not to say that the work is overly tendentious. In fact, S. is careful (usually) to admit that his is not the only possible explanation. When war breaks out, with Crassus’ Carrhae campaign, we learn that this was not simply the fault of one man's covetousness and vainglory (pace Plutarch). Rather, S. argues, Crassus capitalised on a general Roman feeling that Parthia had to be dealt with. His failure, and Antony's, left Rome with a desire for revenge; but S. shows, convincingly, that Octavian/Augustus did not pursue an unremittingly anti-Parthian policy from the beginning of his reign. He sought to stabilise the situation. He had a suitable partner in Phraates IV, who both returned the standards and sent members of his family to reside at Rome: bespeaking an interest in peace at least equal to that of Augustus.

Fittingly, S. treats the Augustan Principate, during which Gaius Caesar and the Parthian Phraataces had a friendly public encounter at the Euphrates, as a high point – equalled only, perhaps, by Neronian diplomatic success in defusing tensions over the Armenian throne. This much is uncontroversial; less so Chapter 7, ‘Legions on the Euphrates’, where we hear that Flavian security measures in the East were undertaken with some opponent other than the Parthians in mind (S. speculates that it was the Scythian Alani).

It all falls apart with Trajan, whose reputation as the ‘Best of Emperors’ rests partly on his Middle Eastern wars, but who was diplomatically a failure and whose acquisitions were largely transitory. S. attributes Trajan's activity in the East to his zeal for glory (backed by Cassius Dio 68.17.1), and he goes on to outline the wars of Lucius Verus, Septimius Severus, Caracalla and Macrinus – all motivated by flimsy pretexts and leading to only temporary gains. By the end of the second century the ‘cycle’ of which S. speaks – initial success at diplomacy, followed by a period of warlike rhetoric leading to real, costly, bloody engagement – had run its course twice through.

While useful and in fact enlightening for the professional historian, the work seems aimed at a wider audience. S.'s erudition is apparent as he examines in detail the ins and outs of dealings between empires, and he interrupts his narrative regularly to review such matters as the political turmoil of the Late Republic, the Second Triumvirate, the Augustan Principate and the Julio-Claudian and Antonine dynasties (naturally the Parthian side of the story is more obscure). This information will be useful to members of the general public, who may well pick up the book in the expectation of learning more about the drums of Carrhae, but who will be surprised to learn that the 300-year history of Roman–Parthian relations featured relatively few bouts of open warfare.

Being human, none of us is perfect, least of all the present reviewer; but some critique is to be expected. Given that the dynamic of peaceful settlement clothed in martial rhetoric is supposed to have applied on both sides, belligerent Parthian propaganda seems to be little in evidence. Parthian coins are supposedly useful in the absence of much other source material; but there are very few illustrations of such coins, and they rarely display the boastfulness of, say, a reverse type illustrating Nero's Parthian arch. Such grandiloquent posturing was not in the Parthian numismatic tradition. In general the illustrations (3 maps and 25 figures in total, all monochrome) serve to illustrate the argument well, although a student unfamiliar with the region may want to seek additional maps elsewhere. Typographical errors are few but occasionally jarring (one suspects that during the Battle of Carrhae the Parthian arrows were piercing rather than ‘perceiving’ Roman armour: p. 68).

There are eight chapters and a conclusion, with Chapter 8 covering the entire century from Trajan to the Severans: an imbalance that S. explains in terms of source considerations and the ‘Trajanic model’ for second-century wars. We conclude with Sassanid Persia: a much more energetic adversary and one truly willing to engage in belligerent militancy – whose rise Rome helped to enable through its exhausting Parthian wars. Finally, S. does not hesitate to draw parallels between the warlike rhetoric of the ancients and the language that has marked the US–Iranian relationship in recent years.

In the end one is left with a question: if, in explaining the origins of war, we end up focusing on political rivalries and individuals’ ambitions, to what extent have we advanced the case beyond the observations of an Arrian, a Plutarch or a Cassius Dio? Perhaps there is truly little else to look for in the way of an explanation; if so, modern historians have been too clever by half.