Valentinian I (; 32117 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 only from February to March of 364, after which he appointed Valens to rule over the Eastern half of the empire, while he remained in control of the West. The founder of the Valentinian dynasty, he is noted for his successful campaigns on the Rhine and Danube frontiers.
Born into a military family in Pannonia, Valentinian rose through the ranks under emperors Constantius II, Julian and Jovian. Following Jovian's early death, Valentinian was proclaimed emperor, and he subsequently selected his brother Valens as co-emperor. During his reign, he fought successfully against the Alamanni, Quadi, and Sarmatians, strengthening the border fortifications and conducting campaigns across the frontiers. In addition, he dispatched his general Theodosius the Elder to suppress a revolt in Africa and the Great Conspiracy, a coordinated assault on Roman Britain by Picts, Scoti, and Saxons. Valentinian suffered a fatal stroke at a meeting with Quadi envoys in Pannonia, with his sons Gratian and Valentinian II succeeding him in the western half of the empire.
Early life Valentinian was born in 321 at Cibalae (now Vinkovci, Croatia) in southern Pannonia into a family of Illyro-Roman origin. Valentinian and his younger brother Valens were the sons of Gratianus (nicknamed Funarius), a military officer renowned for his wrestling skills.
Gratianus was promoted to comes Africae in the late 320s or early 330s, and the young Valentinian accompanied his father to Africa. However, Gratianus was soon accused of embezzlement and retired. Valentinian joined the army in the late 330s and later probably acquired the position of protector domesticus. Gratianus was later recalled during the early 340s and was made comes Britanniarum. After holding this post, he retired to the family estate in Cibalae.
In 350, Constans I was assassinated by agents of the usurper Magnentius, a commander who proclaimed himself emperor in Gaul. Constantius II, older brother of Constans and emperor in the East, promptly set forth towards Magnentius with a large army. The following year the two emperors met in Pannonia and fought the Battle of Mursa Major, which ended in a costly victory for Constantius. Two years later Magnentius killed himself after another defeat at the Battle of Mons Seleucus, leaving Constantius sole ruler of the empire. It was around this time that Constantius confiscated Gratianus' property, for supposedly showing hospitality to Magnentius when he was in Pannonia. Despite his father's fall from favour, Valentinian does not seem to have been adversely affected at this time, making it unlikely he ever fought for the usurper. It is known that Valentinian was in the region during the conflict, but what involvement he had in the war, if any, is unknown.
Service under Constantius and Julian
During the conflict between Magnentius and Constantius, the Alamanni and Franks took advantage of the confusion and crossed the Rhine, attacking several important settlements and fortifications. In 355, after deposing his cousin Gallus but still feeling the crises of the empire too much for one emperor to handle, Constantius raised his cousin Julian to the rank of Caesar. With the situation in Gaul rapidly deteriorating, Julian was made at least nominal commander of one of the two main armies in Gaul, Barbatio being commander of the other. Constantius devised a strategy where Julian and Barbatio would operate in a pincer movement against the Alamanni. However, a band of Alamanni slipped past Julian and Barbatio and attacked Lugdunum (Lyon). Julian sent the tribunes Valentinian and Bainobaudes to watch the road the raiders would have to return by. However, their efforts were hindered by Barbatio and his tribune Cella. The Alamanni king Chnodomarius took advantage of the situation and attacked the Romans, inflicting heavy losses. Barbatio complained to Constantius and the debacle was blamed on Valentinian and Bainobaudes, who were cashiered from the army.
With his career in ruins, Valentinian returned to his new family estate in Sirmium (in modern day Serbia). Two years later his first wife Marina Severa had given birth to a son, Gratian. During the (sole) reign of the polytheist Julian, Valentinian's actions and location become uncertain, but he was likely exiled, or perhaps simply sent to command a remote outpost. The sources give contradictory accounts of what happened, with some versions saying that he refused to make pagan sacrifices and voluntarily chose to leave, and others saying he was merely dismissed for his Christianity.Jones, A.H.M.; Martindale, J.R. (1971). The Prosopography of the Later Roman Empire, Vol. I: AD 260–395. Cambridge University Press. p. 933.
Rise to power At the news of Julian's death on a campaign against the Sasanian Empire, the army hastily declared Jovian the new emperor. Jovian extricated his soldiers from Persian territory by agreeing to a humiliating peace treaty, then started back to Constantinople. During Jovian's brief reign Valentinian was promoted to tribune of a Scutarii (elite infantry) regiment, which Hughes considered to reflect the new emperor’s trust in him, and dispatched to Ancyra (modern day Ankara).
Jovian died in mysterious circumstances before he reached the capital, and a meeting of civil and military officials was convened at Nicaea to choose a new emperor. Salutius, who had already refused the throne after Julian's death, now did so again, first for himself and then on behalf of his son.Edward Gibbon, The Decline and Fall of the Roman Empire, (The Modern Library, 1932), ch. XXV., pp. 845, 846 Two other names were proposed: Aequitius, a tribune of the first Scutarii, and Januarius, a relative of Jovian's in charge of military supplies in Illyricum. Both were rejected; Aequitius as too rough and boorish, Januarius because he was too far away. The assembly finally agreed upon Valentinian, as a man both well qualified and nearby, and sent messengers to inform him in Ancyra.
Reign
Valentinian accepted the acclamation on 25 or 26 February 364. As he prepared to make his accession speech, the soldiers threatened to riot, apparently uncertain of his loyalties. Valentinian reassured them that the army was his greatest priority. According to Ammianus the soldiers were astounded by Valentinian's bold demeanour and his willingness to assume the imperial authority. To further prevent a succession crisis he agreed to pick a co-Augustus, perhaps as a reassurance to civilian officials in the Eastern part of the Empire that someone with imperial authority would be present to protect their interests.
Valentinian selected his brother Valens as co-Augustus at Constantinople on 28 March 364. This was done over the objections of Dagalaifus, the magister equitum. Ammianus makes it clear that Valens was subordinate to his brother. The remainder of 364 was spent delegating administrative duties and military commands. According to the 5th century pagan historian Zosimus, who was inclined to revile the restorer of Christianity, all the ministers and officials appointed by Julian were summarily dismissed in disgrace. This assertion was qualified by modern authorities.Gibbon, p. 849 note It is certain that some reshuffling of commands occurred along with the division of the provinces, but the changes were strictly based on merit. Valentinian retained the services of Dagalaifus and promoted Aequitius to Comes Illyricum. Valens was given the Praetorian prefecture of the East, governed by prefect Salutius. Valentinian gained control of Italy, Gaul, and Illyricum. Valens resided in Constantinople, while Valentinian's court was situated in Milan (Mediolanum).
Campaigns in Gaul and Germania
In 365 the Alemanni crossed the Rhine and invaded Gaul. Simultaneously, Procopius began his revolt against Valens in the east. According to Ammianus, Valentinian received news of both crises on 1 November while on his way to Lutetia. He initially sent Dagalaifus to fight the AlemanniAmmianus Marcellinus, Res Gestae XXVI.5.9 while he himself made preparations to march east and help Valens. After receiving counsel from his court and deputations from the leading Gallic cities begging him to stay and protect Gaul, he decided to remain and fight the Alemanni.Ammianus Marcellinus, Res Gestae XXVI.5.12Ammianus Marcellinus, Res Gestae XXVI.5.13 Valentinian advanced to Durocortorum and sent two generals, Charietto and Severianus, against the invaders.Ammianus Marcellinus, Res Gestae XXVII.1.2 Both generals were promptly defeated and killed;Ammianus Marcellinus, Res Gestae XXVII.1.4 Dagalaifus took their place in 366, but he was also ineffective.Ammianus Marcellinus, Res Gestae XXVII.2.1 Late in the campaigning season Dagalaifus was replaced by Jovinus, a general from the court of Valentinian. After several victories along the Meuse river, Jovinus fought and won a pitched battle with the Alemanni near Chalôn.Ammianus Marcellinus, Res Gestae XXVII.2.1–7 After his victory he pushed the Alemanni out of Gaul and was awarded the consulate the following year for his efforts.Ammianus Marcellinus, Res Gestae XXVII.2.10
In early 367, crises in Britain and northern Gaul postponed Valentinian's punitive expedition against the Alemanni, who promptly re-crossed the Rhine and plundered Mogontiacum. Valentinian succeeded in arranging the assassination of Vithicabius, an Alemannic leader, but wanted to decisively end the conflict by bringing the Alemanni under Roman hegemony. Valentinian spent the entire winter of 367 gathering a massive army for a spring offensive. He summoned the Comes Italiae Sebastianus, with the Italian and Illyrian legions, to join Jovinus and Severus, the magister peditum. In the spring of 368 Valentinian, his eight-year-old son Gratian and the army crossed the Rhine and Main rivers into Alemannic territory. Initially they encountered no resistance, burning any dwellings or food stores they found along the way. Finally, Valentinian fought the Alemanni in the Battle of Solicinium; the Romans were victoriousAmmianus Marcellinus, Res Gestae XXVII.10.15 but suffered heavy casualties.Ammianus Marcellinus, Res Gestae XXVII.10.16 A temporary peace was reached and Valentinian returned to Trier for the winter.Ammianus Marcellinus, Res Gestae XXVII.10.17 During 369, Valentinian ordered new defensive works to be constructed and old structures refurbished along the length of the Rhine's west bank.Ammianus Marcellinus, Res Gestae XXVIII.2.1 Boldly, he ordered the construction of a fortress across the Rhine in the mountains near modern Heidelberg.Ammianus Marcellinus, Res Gestae XXVIII.2.2 The Alemanni sent envoys to protest, but they were dismissed. The Alemanni attacked the fortress while it was still under construction and destroyed it.Ammianus Marcellinus, Res Gestae XXVIII.2.8
In 370 the Saxons renewed their attacks on northern Gaul. Nannienus, the comes in charge of the troops in northern Gaul, urged Severus to come to his aid. After several modest successes, a truce was called and the Saxons handed over young men fit for duty in the Roman military, in exchange for free passage back to their homeland. The Romans ambushed them and destroyed the entire invading force.Rike, R.L., Apex Omnium: Religion in the Res Gestae of Ammianus (1987), p.. 91; Jones, Martindale and Morris, The Prosopography of the Later Roman Empire Vol. I (1971), pp. 615–616