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(Flavius Gratianus). Born 359 in Sirmium; died 383 in Lugdunum. Roman emperor of the western part of the empire (reigned from 367 to 383). In 367 he became coruler with his father, Valentinian I (364–375). After the latter’s death, Gratian inherited the western part of the empire (in the eastern part, Valens ruled from 364 to 378 and Theodosius I beginning in 379). Under the influence of Ambrose of Milan. Gratian became an ardent defender of Christianity and deprived the pagan priesthood of its income and privileges. In 382 he ordered the altar of Victory—a symbol of paganism— to be taken out of the Senate. After 378 he fought against the Alamanni and the Goths.