Once at Ctesiphon, Odaenathus immediately began a siege of the well-fortified winter residence of the Persian kings; severe damage was inflicted upon the surrounding areas during several battles with Persian troops. The city held out and the logistical problems of fighting in enemy territory probably prompted the Palmyrenes to lift the siege. Odaenathus headed north along the Euphrates carrying with him numerous prisoners and much booty. The invasion resulted in the full restoration of the Roman lands which had been occupied by Shapur I since the beginning of his invasions in 252: Osroene and Mesopotamia. However, Dura-Europus and other Palmyrene posts south of Circesium, such as Anah, were not rebuilt. Odaenathus sent the captives to Rome, and by the end of 263 Gallienus assumed the title "Persicus maximus" ("the great victor in Persia") and held a triumph in Rome.