Excerpts from Books and Wikipedia
"Valentinian's reign is marked by the dismemberment of the Western Empire; by the time of his death, virtually all of North Africa, all of western Spain, and the majority of Gaul had passed out of Roman hands. He is described as spoiled, pleasure-loving, and heavily influenced by sorcerers and astrologers. Valentinian was devoted to religion, contributing to churches of Saint Lawrence in both Rome and Ravenna. He also handed over greater authority to the Papacy. On 6 June 445, he issued a decree which recognized the primacy of the bishop of Rome based on the merits of Saint Peter, the dignity of the city, and the Nicene Creed (in their interpolated form); ordained that any opposition to his rulings, which were to have the force of ecclesiastical law, should be treated as treason; and provided for the forcible extradition by provincial governors of anyone who refused to answer a summons to Rome." [Wikipedia]