Trajan's Parthian campaign, also known as Trajan's Parthian War, was engaged by Roman emperor Trajan in the year 115 against the Parthian Empire in Mesopotamia.
The war was initially successful for the Romans, but due to a series of setbacks, including wide-scale rebellions in the Eastern Mediterranean and North Africa, as well as Trajan's death in 117, ended in a Roman withdrawal.

In 113, 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, 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, the Roman emperor overran northern Mesopotamia and annexed it 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 the Eastern Mediterranean, North Africa and northern Mesopotamia, while a major Jewish revolt broke out in Roman territory, severely stretching Roman military resources.
Trajan failed to take Hatra, which avoided total Parthian defeat.
Parthian forces attacked key Roman positions, while Roman garrisons at Seleucia, Nisibis and Edessa were evicted by the local populaces.
Trajan subdued the rebels in Mesopotamia, installed the Parthian prince Parthamaspates as a client ruler, and withdrew to Syria.
Trajan died in 117, before he could renew the war.

Trajan's Parthian campaign is considered, in different ways, the climax of "two centuries of political posturing and bitter rivalry."
Trajan was the first emperor to carry out a successful invasion of Mesopotamia.
His grand scheme for Armenia and Mesopotamia were ultimately "cut short by circumstances created by an incorrect understanding of the strategic realities of eastern conquest and an underestimation of what insurgency can do."
Trajan's Parthian campaign, also known as Trajan's Parthian War, was engaged by Roman emperor Trajan in the year 115 against the Parthian Empire in Mesopotamia. The war was initially successful for the Romans, but due to a series of setbacks, including wide-scale rebellions in the Eastern Mediterranean and North Africa, as well as Trajan's death in 117, ended in a Roman withdrawal. 
In 113, 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, 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, the Roman emperor overran northern Mesopotamia and annexed it 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 the Eastern Mediterranean, North Africa and northern Mesopotamia, while a major Jewish revolt broke out in Roman territory, severely stretching Roman military resources. Trajan failed to take Hatra, which avoided total Parthian defeat. Parthian forces attacked key Roman positions, while Roman garrisons at Seleucia, Nisibis and Edessa were evicted by the local populaces. Trajan subdued the rebels in Mesopotamia, installed the Parthian prince Parthamaspates as a client ruler, and withdrew to Syria. Trajan died in 117, before he could renew the war. 
Trajan's Parthian campaign is considered, in different ways, the climax of "two centuries of political posturing and bitter rivalry." Trajan was the first emperor to carry out a successful invasion of Mesopotamia. His grand scheme for Armenia and Mesopotamia were ultimately "cut short by circumstances created by an incorrect understanding of the strategic realities of eastern conquest and an underestimation of what insurgency can do."
Trajan's Parthian campaign