Introduction

From the time of Pompey’s establishment of the province of Syria in c.65bc, the Euphrates came to symbolize a boundary between Roman and Parthian interests in the Near East.1 On a number of occasions over the next 130 years meetings between senior Roman officials or members of the Imperial family and Parthian representatives were held on the Euphrates, confirming its status during this time as a boundary. During this time, however, there is no evidence for Roman fortifications within the vicinity of the Euphrates, and the river was crossed on many occasions by both Roman and Parthian forces. The Euphrates appears to have played the role of a symbolic boundary between Roman and Parthian interests up to the early Flavian period. Initially the status of the river as a symbolic boundary applied more to its northerly section as it flows from north to south, but during the Augustan period there is some evidence to suggest that it came to include the middle Euphrates in its south-easterly flow towards Mesopotamia.2

Over time the Euphrates came to play an increasingly important military role in the disputes between Rome and Parthia over Armenia, and this was one factor that led to the permanent establishment of Roman troops on or close to the river for the first time during the reign of Vespasian. In the second century the Euphrates played a key role in conflict between Rome and Parthia, including three Roman invasions of its powerful eastern neighbour. As Roman territorial interests extended further east as a result of these conflicts, the Euphrates became increasingly important militarily over an increasing distance. By the end of the second century AD, Rome had organized territory for a considerable distance on the other side of the Euphrates so that Roman provincial territory extended to the banks of the Tigris.3 By this time, the Euphrates itself became less important militarily as the frontier moved further east but there is considerable evidence for the Roman military presence on the middle Euphrates in the third century AD.

From Pompey to Vespasian the more relevant section of the Euphrates as a symbolic boundary was the course it took as it flows south from Cappadocia and Commagene to the point where it turns east near Bar-balissos to flow in the direction of Mesopotamia. From this point the evidence is less conclusive; however, in the late first century BC the confluence of the Khabur river and the Euphrates may also have marked a boundary between Roman and Parthian interests. In general, the Euphrates was not well suited to act in a defensive capacity for Rome, but there were times when practicality saw it act in this way.4 At its most westerly stretch the Euphrates flows close to the Mediterranean coastline in the direction of Antioch, making the most important city in the Roman Near East potentially vulnerable to Parthian and, later, Persian attacks directed from the river. Despite this, fortifications on or close to the river under the Flavians and Trajan were located more to the north, indicating that the main military interest was in Armenia and increasingly in directing attacks into Osrhoene and northern Mesopotamia. In the long term, therefore, the military build-up that developed under the Flavians on the upper and middle Euphrates was focused more on offensive capacity than defence.

While the Roman military presence on the middle and upper Euphrates was maintained in the second century, it appears that there were no Roman fortifications on the river below Zeugma until after the victory over Parthia in the middle of the second century under Lucius Verus. From this period a larger section of the Euphrates came under more direct Roman control, with Roman fortifications located as far down the river as Dura Europos. By the end of the reign of Septimius Severus, Roman fortifications existed on the Euphrates a further 120 km downstream from Dura. Prior to AD 165, settlements on the Euphrates below the Khabur, such as Dura, had been under some form of Parthian control, but there are important questions to be asked about the nature of Parthian control on this section of the middle Euphrates and, in particular, the nature of the Palmyrene presence on this part of the river in the second century. As Roman power extended further east towards Mesopotamia in the second century, the Palmyrenes came to play an increasingly important military role in the Roman presence on the Euphrates. This military role was an evolution from the armed protection of the caravans, which Palmyra had established from the first century bc. When Septimius Severus initiated a major reorganization of territory in Syria, Osrhoene and northern Mesopotamia, the Palmyrenes continued to play a significant role in the longer-term establishment of Roman authority on the middle Euphrates and in the territory of Palmyra itself. Following its inclusion in the province of Coele Syria, Palmyra would continue to play a unique role in the Roman Near East, which in turn contributed to its dramatic rise and fall later in the third century.