Rome versus Parthia
The Romans and Parthians fought a series of wars beginning with Crassus' invasion in 52-53 BC and ending with Macrinus' ignominious defeat and retreat in 217 AD. During this time it became clear to both sides that a natural boundary existed in northern Mesopotamia beyond which it was difficult, if not impossible, for either side to maintain a permanent foothold. The Parthians were generally less aggressive than the Romans, and generally sought to maintain the status-quo, particularly with regard to Armenia, in part because they were nearly constantly engaged in suppressing internal rebellions, fighting civil wars, or defending their eastern borders. The Romans invaded Parthian territory under Crassus, Mark Antony, Nero, Trajan, Lucius Verus, Marcus Aurelius, Septimius Severus, Caracalla and Macrinus. The only lasting result of these invasions was the takeover of part of northern Mesopotamia by Trajan in 116 AD, a permanent loss to Parthia which was enlarged under Lucius Verus in 165 AD. The following maps show:
The traditional border between Rome and Parthia, lasting until Trajan's invasion.
Changes in the border brought on by first by Trajan and, later, by Lucius Verus.
Parthian invasion routes into Roman territory, including Armenia.
Roman invasion routes into Parthian territory, including major battle sites.