Because of its importance, Ctesiphon was a major military objective for the leaders of the Roman Empire in their eastern wars. The city was captured by Rome five times in its history – three times in the 2nd century alone. The emperor Trajan captured Ctesiphon in 116, but his successor, Hadrian, decided to willingly return Ctesiphon in 117 as part of a peace settlement. The Roman general Avidius Cassius captured Ctesiphon in 164 during another Parthian war, but abandoned it when peace was concluded. In 197, the emperor Septimius Severus sacked Ctesiphon and carried off thousands of its inhabitants, whom he sold into slavery.