Valentinian I (321 – 17 November 375), sometimes known as Valentinian the Great, was Roman emperor from 364 to 375. He is the second-last emperor to govern the empire as a whole, albeit he only did so from February 26th to March 28th of 364, after which he appointed Valens to rule over the Eastern half the empire, while he remained in control of the West. During his reign, he fought successfully against the Alamanni, Quadi, and Sarmatians, strengthening the border fortifications and conducting campaigns across the Rhine and Danube. Also, his general Theodosius the Elder defeated a revolt in Africa and the Great Conspiracy (a coordinated assault on Roman Britain by Picts, Scoti, and Saxons). Valentinian founded the Valentinian dynasty, with his sons Gratian and Valentinian II succeeding him in the western half of the empire and his daughter Galla marrying emperor Theodosius I.