Flavius Valentinianus was born in 321 and was the son of a successful general named Gratian the Elder.
During his military career he was an officer of the Praetorian Guard under both Julian and Jovian and continued to rise through the ranks of the imperial service.
Following the death of Jovian he was elected emperor by officers of the army because of his great courage and military capacity. His brother Valens accompanied him on most expeditions and together they shared power over the empire with Valentinian taking rule over the western empire and Valens controlling the eastern empire.
It was at this time that the Saxon and Burgundian barbarians introduced themselves and the two brothers spent much time subduing their attacks.
It was the Alamanni that proved Valentinians biggest problem when they crossed the Rhine and plundered the city. Even though Valentinian’s attack on them was successful, the losses that his own army sustained were so great that he didn’t continue and instead chose to make peace with their king, Macrianus, and following this peace deal they developed a friendship.
In 374 following the erection of roman forts on what they claimed to be their land, a Germanic tribe by the name of Quadi crossed the river and completely desecrated the city of Pannonia. During an assembly with the Quadi in 375, while Valentinian was angrily yelling, a blood vessel burst in his skull causing his immediate death.