After the Departure of Valens from Antioch, the Alexandrians expel Lucius, and restore Peter, who had come with Letters from Damasus Bishop of Rome
About the same time, as soon as the Emperor Valens left Antioch, all those who had anywhere been suffering persecution began again to take courage, and especially those of Alexandria. Peter returned to that city from Rome, with letters from Damasus the Roman bishop, in which he confirmed the 'homoousian' faith, and sanctioned Peter's ordination. The people therefore resuming confidence, expelled Lucius, who immediately embarked for Constantinople: but Peter survived his re-establishment a very short time, and at his death appointed his brother Timothy to succeed him.
Source: Ecclesiastical History (New Advent)