Valentinian I

in full Flavius Valentinianus

(born AD 321, Cibalae, Pannonia—died Nov. 17, 375, Brigetio, Pannonia Inferior) Roman emperor (364–375). He served in the military in Africa under his father. Proclaimed emperor by the army, he made his brother Valens ruler in the East while he ruled the West. Both agreed to allow religious toleration, which Valentinian, unlike Valens, maintained throughout his reign. He defeated the Alemanni in Gaul in 365, then moved to support the defense of Britain. He named his nine-year-old son Gratian coemperor (367) to ensure succession. In Germany he fortified the Rhine; he went on to fight the Quadi in Pannonia, where he fell sick and died. Despite his achievements, he was known for his cruelty and poor choice of ministers.

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