Conclusion

The extension of formal Roman control of territory - from the relatively small coastal province of Syria as it was established by Pompey to the considerable territory that comprised the provinces of Coele Syria, Syria Phoenice, Cappadocia, Mesopotamia and Osrhoene under Septimius Severus and his successors - represents impressive territorial gains for the Romans over a period of almost 300 years. Viewed over this period the expansion appears inexorable and unstoppable. There were, however, many difficulties and setbacks along the way, and the resources invested in undertaking some of this expansion were called into serious question in the early decades of the third century ad. The Euphrates river played a pivotal role in the development of Roman power through this period. The Roman military presence on the river grew and was at times considerable, but the defence of Roman territory, in particular Syria, was only one of a number of roles that the fortifications located along it played. The river at times acted in a defensive capacity, and the fortifications on its banks were useful for this purpose. This was not necessarily the immediate intention of these fortifications, but in practice they came to be important for defence at times. The presence of fortifications on or near the river north from Zeugma not only allowed Roman troops easier access to Armenia but offered better protection to cappadocia and Syria in the event of a major invasion. Osrhoene and Mesopotamia could be attacked by the Romans using the bridge crossing at Zeugma, but Zeugma was itself seen as providing security against Parthian attacks. The fortifications that had been placed on the upper and middle Euphrates under Vespasian had considerably strengthened Rome’s hand in Armenia, while the section of the Euphrates from Europos to Sura had seen heavy fighting under Lucius Verus. The Euphrates had acted as a boundary between Rome and Parthia up to the reign of Lucius Verus and it became the basis of a line of fortifications on its upper reaches that served defensive and offensive purposes.

The Parthian wars of Septimius Severus and their aftermath saw important changes to the nature of Roman control in Syria and Mesopotamia. These came to have a profound effect on Rome’s relationship with the Parthian Empire in its last years, and particularly with the Sasanian Persians. The reign of Septimius Severus saw the formal establishment of Roman power in Mesopotamia with the formation of a Roman province garrisoned by two permanent legions. His reign also saw the division of Syria into two new provinces and the establishment of numerous fortifications on the middle Euphrates and Khabur rivers. The period of Severus’ rule also provides the earliest clear evidence of the formal inclusion of Palmyra within provincial territory. A province of Osrhoene was established and a much-reduced client-kingdom of Edessa maintained. Roman power now formally extended across the Euphrates into northern Mesopotamia as far as the upper Tigris. The Euphrates below the Khabur confluence was also under Roman control and experienced a military presence. The territory in between this stretch of the Euphrates and the Tigris was partly controlled by the kingdom of Hatra, but east of the Euphrates and west of the Tigris below Dura lay inhospitable land that probably acted as a natural barrier to troops from either empire. Below the Khabur, the Euphrates was a major transport route and its irrigated banks were an area of important agricultural production.134 This is particularly important to the history of the region in the first half of the third century ad. The results of Septimius Severus’ actions saw much of Rome’s power and influence across the Euphrates formally organized and the development of a frontier zone that was based more on the Tigris. The Roman Empire had now formally extended as far east as it had ever been and the Parthians seem to have been unable to challenge this expansion effectively. For the Romans, it would be a very different story following the overthrow of the Parthians by the Sasanian Persians approximately 30 years later.