Tiberius, the son born in 42 b.c. to Ti. Claudius Nero and Livia, had lived through many changes of fortune. First, he became the stepson of Octavian who had married his mother after her divorce from Claudius in 38. With his younger brother Drusus he had been granted many privileges by Augustus whom he had accompanied on journeys both to the West and East; in 20 he had received the lost standards from the Parthians. He then served with distinction on the northern frontier, and held the consulship first in 13 and again in 7 b.c. But he had been compelled to divorce his wife Vipsania Agrippina (daughter of Agrippa and the mother of his son Drusus) whom he loved, in order to marry Augustus' daughter Julia (Agrippa's widow) in 11 b.c.; this marriage was not successful. He was given tribunicia potestas for five years in 6 b.c. and was offered a diplomatic mission in the East, but to Augustus' annoyance Tiberius preferred to retire to Rhodes where he passed eight years in virtual exile; dislike of his wife and a growing realization that he had been forced to marry her only in order to protect the interests of her children, the princes Gaius and Lucius, will have contributed to his decision. He enjoyed the cultural life of the island, until through Livia's help he was enabled to return to Rome, though not to the favour of Augustus, in a.d. 2. Two years later the scene had changed dramatically: the two heirs apparent were dead, and once again Augustus' plans had been brought to nought. He therefore turned again, though with reluctance, to his stepson Tiberius, who was adopted as his son, received tribunicia potestas for ten years, and was granted a special command (proconsular imperium) on the northern frontier; but even so he was compelled to adopt his nephew Germanicus as his son, though he 227already had a son of his own, Drusus. Then came years of fine military service which put the Roman world deeply in his debt, when he crushed the revolts in Pannonia and Illyricum and then saved the situation on the German front after the disaster to Varus. After his return to Rome he triumphed in a.d. 12, and in the following year his tribunician power was prolonged and he received proconsular imperium like that held by the emperor: he became in fact almost a co-regent, though he lacked above all the auctoritas of Augustus.