During his reign, he fought successfully against the Alamanni, Quadi, and Sarmatians, strengthening the border fortifications and conducting campaigns across the Rhine and Danube.

His general Theodosius defeated a revolt in Africa and the Great Conspiracy, a coordinated assault on Roman Britain by Picts, Scoti, and Saxons.

[6] Valentinian and his younger brother Valens were the sons of Gratianus (nicknamed Funarius), a military officer renowned for his wrestling skills.

[15] 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.

[22][21] During the sole reign of the polytheist Julian, Valentinian's actions and location become uncertain, but he was likely exiled,[c] or perhaps simply sent to command a remote outpost.

[23] 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.

[25] During Jovian's brief reign Valentinian was promoted to tribune of a Scutarii (elite infantry) regiment, which Hughes considered to reflect the Emperor’s trust in him, and dispatched to Ancyra.

[26] 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.

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.

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.

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.

[41] 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 Moguntiacum.

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.

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.

In 374 Valentinian was forced to make peace with Macrian because the Emperor's presence was needed to counter an invasion of Illyricum by the Quadi and Sarmatians.

Valentinian received reports that a combined force of Picts, Attacotti and Scots had attacked the province, killing the Comes litoris Saxonici Nectaridus and Dux Britanniarum Fullofaudes.

Later, he rallied the remaining garrison which was originally stationed in Britain; it was apparent the units had lost their cohesiveness when Fullofaudes and Nectaridus had been defeated.

Romanus took sides in the murderous disputes among the legitimate and illegitimate children of Nubel, a Moorish prince and leading Roman client in Africa.

Resentment of Romanus's personal use of public funds and his failure to defend the province from desert nomads caused some of the provincials to revolt.

However, the increasingly influential minister Maximinus, now praetorian prefect of Gaul, blamed Aequitius to Valentinian for the trouble, and managed to have him promote his son Marcellianus to finish the project.

He arrived on 17 November 375 and had a hostile meeting with a Quadi deputation,[56] who received permission for their people to leave in peace in return for supplying fresh recruits to the Roman army.

Jones writes that although Valentinian I was "less of a boor" than his chief rival for election to the imperial throne, "he was of a violent and brutal temper, and not only uncultivated himself, but hostile to cultivated persons".

According to Ammianus, "he hated the well-dressed and educated and wealthy and well-born", which suggests Valentinian had his enemies in Rome who wanted to defame him by describing him as an uneducated brute.

This was not a complete picture: Ammianus concedes that Valentinian had some spontaneous oratorical skill, and also says that in his spare time the Emperor was "an elegant painter and modeller [i.e., sculptor], and an inventor of new kinds of [weapons]" (XXX.9.4).

[59] He appointed the Latin scholar Ausonius as tutor for his son Gratian,[60] showing an appreciation for the kind of classical education which he himself had been denied.

He often had servants and attendants executed on trifling charges, and was reportedly accustomed to feed his victims to two bears, known as Mica Aurea (golden flake), and Innocence, whose iron cage was transported wherever the emperor went.

At length Innocence, when she was considered to have faithfully discharged her office, was released with Valentinian's good wishes into her native wilds.

[64] Valentinian was a Christian but permitted liberal religious freedom to all his subjects, proscribing only some forms of rituals such as particular types of sacrifices, and banning the practice of magic.

One new law, issued via Pope Damasus I, prohibited the granting of bequests to clergymen, and another said that members of the sacerdotal order must discharge the public duties owed on account of their property, or else relinquish it.

[71] A more flattering physical description of Valentinian is given by Ammianus (XXX.9.6), who praises the emperor's "strong and muscular body, his brilliant complexion, his grey eyes, with a gaze that was always sidelong and stern, his fine stature, and his regular features".