Valentinian I

Valentinian I (321–375), born at Cibalae in Pannonia to an Illyro-Roman military family, rose in rank under Constantius II, Julian and Jovian, and after Jovian's death was proclaimed emperor in February 364. Weeks later he made his brother Valens co-emperor at Constantinople, keeping the Western provinces for himself.

He campaigned successfully against the Alamanni, Quadi and Sarmatians and strengthened the Rhine and Danube frontiers. On 17 November 375, enraged by Quadi envoys at Brigetio, he died of a stroke; his sons Gratian and Valentinian II succeeded him.