Valens (väˈlənz) [key], c.328–378, Roman emperor of the East (364–78). Brother and coregent of Valentinian I, Valens followed in most respects his brother's policies but, unlike him, embraced Arian Christianity (see Arianism). An intolerant man, he sporadically persecuted orthodox Christians. At the beginning of his reign he put down the revolt of Procopius. He initiated warfare against the Visigoths under Athanaric and defeated them in 369. His attitude toward the Persian threat to Armenia was indecisive, but in 376 peace was made. He admitted the Visigoths under Fritigern into the empire. Dissatisfied with the Romans, they rebelled, and in 378, Valens was killed in the battle of Adrianople, in which two thirds of the Roman army was destroyed, leaving the Eastern Empire virtually defenseless. He was succeeded by Theodosius I.