Trajan's Parthian War
A new series of wars began in the 2nd century AD, during which the Romans consistently held the upper hand over Parthia. In 113 AD the Roman Emperor Trajan decided that the moment was ripe to resolve the "eastern question" once and for all time by the decisive defeat of Parthia and the annexation of Armenia; his conquests marked a deliberate change of Roman policy towards Parthia, and a shift of emphasis in the "grand strategy" of the empire.
In 114 AD Trajan invaded Armenia, annexed it as a Roman province, and killed Parthamasiris who was placed on the Armenian throne by his relative, the king of Parthia, Osroes I. In 115 AD the Roman emperor overran northern Mesopotamia and annexed to Rome as well; its conquest was deemed necessary, since otherwise the Armenian salient could be cut off by the Parthians from the south. The Romans then captured the Parthian capital, Ctesiphon, before sailing downriver to the Persian Gulf. However, in that year revolts erupted in Palestine, Syria and northern Mesopotamia, while a major Jewish revolt broke out in Roman territory, severely stretching Roman military resources. Simultaneously, Parthian forces began attacking key Roman positions; at the same time the Roman garrisons at Seleucia, Nisibis and Edessa had been attacked and evicted by the local populaces. Trajan subdued the rebels in Mesopotamia, but having installed the Parthian prince Parthamaspates on the throne there as a client ruler he withdrew his armies, and proceeded to Syria, where he set up his headquarters at Antioch. In 117, before he could reorganize the effort to consolidate Roman control over the Parthian provinces, Trajan died.