Trajan. 98-117 AD. Æ Sestertius 32 mm. 26.1 gm. Struck 116-117 AD. Obv: IMP CAES NER TRAIANO OPTIMO AVG GER DAC PARTHICO P M TR P COS VI P P, laureate and draped bust right Rev: ARMENIA ET MESOPOTAMIA IN POTESTATEM P R REDACTAE, S C across field, Trajan, laureate and in military uniform, standing facing, head right, holding reversed spear and parazonium; Mesopotamia seated left at feet, in attitude of mourning; to left and right, Tigris and Euphrates seated vis à vis, each leaning on inverted urn from which water flows, and holding reed. RIC II 642; Strack 472; Banti 29; BMCRE 1033; Cohen 39.
Trajan's final campaign was sparked by Parthia's replacement of the pro-Roman king of Armenia with one of their own in 114 AD. Armenia had been a strategic and semi-independent kingdom which served as an important buffer between Parthia and Rome. The last conflict overt this region, during Nero's reign, resulted in a delicate balance that stabilized the situation for over fifty years. The move by Parthia now upset the balance and posed a threat to Rome's wealthy Syrian cities. Trajan’s campaign was swift and decisive; by 115 AD, Armenia was restored as a Roman client state. To secure the eastern frontier, he then moved southward through Mesopotamia, and captured the Parthian capital, Ctesiphon, in 116 AD. Although short-lived, these victories were celebrated on much of Trajan's later coinage.