Editing Gratian (section)

=== Junior ''augustus'' ===
Valentinian, concerned with Gratian's age and inexperience, stated his son would assist commanders with upcoming campaigns.{{sfn|Hebblewhite|2019|pp=18–19}}  The ''[[magister peditum]]'' [[Merobaudes (magister peditum)|Merobaudes]], together with the [[Comes rei militaris|''comes'' ''rei militaris'']] [[Sebastianus (magister peditum)|Sebastianus]], was sent by Valentinian to campaign against the [[Quadi]].<ref name=":0">{{PLRE|title=Sebastianus 2|article=|volume=1|pages=812–813}}</ref>

When a party of [[Alamanni]] visited Valentinian's headquarters to receive the customary gifts towards the end of 364, Ursatius, the ''[[magister officiorum]]'' made them an offering they considered inferior to that of his predecessor. Angered by Ursatius' attitude, they vowed revenge and crossed over the Rhine into Roman [[Germania]] and Gaul in January 365, overwhelming the Roman defences.{{sfn|Curran|1998|p=83}} Although at first unsuccessful, eventually [[Jovinus (consul)|Jovinus]], the ''[[magister equitum]]'' in Gaul inflicted heavy losses on the enemy at Scarpona ([[Dieulouard]]) and at [[Catalauni]] ([[Châlons-sur-Marne]]), forcing them to retire.{{sfn|Curran|1998|p=83}} An opportunity to further weaken the Alamanni occurred in the summer of 368, when king [[Vithicabius]] was murdered in a coup, and Valentinian and his son Gratian crossed the river Moenus (the [[Main (river)|Main]]) laying waste to Alamannic territories.{{sfn|Kienast|2017c}}{{sfn|Curran|1998|p=84}}  Gratian was awarded the victory titles of ''Germanicus Maximus'' and ''Alamannicus Maximus'', and ''Francicus Maximus'' and ''Gothicus Maximus'' in 369.{{sfn|Kienast|2017c}}

Valentinian fortified the frontier from [[Raetia]] in the east to the Belgic channel, but the construction was attacked by Alamanni at Mount Pirus (the Spitzberg, [[Rottenburg am Neckar]]). In 369 (or 370) Valentinian then sought to enlist the help of the [[Burgundians]], who were involved in a dispute with the Alamanni, but a communication failure led to them returning to their lands without joining forces with the Romans.{{sfn|Curran|1998|p=84}} It was then that the ''[[magister equitum]]'', [[Theodosius the Elder]] and his son Theodosius (the Theodosi) attacked the Alamanni through [[Raetia]], taking many prisoners and resettling them in the [[Po Valley]] in Italy.{{sfn|Curran|1998|p=84}} Valentinian made one attempt to capture [[Macrian]]us in 372, but eventually made peace with him in 374.{{sfn|Curran|1998|p=85}}

Gratian, who was then 15, was married in 374 to [[Constantius II]]'s 13 year-old posthumous daughter [[Constantia (wife of Gratian)|Constantia]] at [[Trier]].{{sfn|Curran|1998|p=85}}{{sfn|Lenski|2002|p=103}}{{sfn|McEvoy|2013|p=105}}

The necessity to make peace was the increasing threat from other peoples, the [[Quadi]] and the [[Sarmatians]]. Valentinian's decision to establish garrisons across the Danube had angered them, and the situation escalated after the Quadi king, [[Gabinia gens|Gabinus]], was killed during negotiations with the Romans in 374. Consequently, in the autumn, the Quadi crossed the Danube plundering Pannonia and the provinces to the south.{{sfn|Curran|1998|p=85}} The situation deteriorated further once the Sarmatians made common cause inflicting heavy losses on the Pannonica and Moesiaca legions.{{sfn|Curran|1998|p=85}} However, on encountering Theodosius' forces on the borders of [[Moesia]] in the eastern Balkans, which had previously defeated one of their armies in 373, they sued for peace.{{sfn|Curran|1998|p=85}} Valentinian mounted a further offensive against the Quadi in August 375, this time using a [[pincer movement]], one force attacking from the northwest, while Valentinian himself headed to [[Aquincum]] (Budapest), crossed the Danube and attacked from the southeast.{{sfn|Curran|1998|p=85}} This campaign resulted in heavy losses to the enemy, following which he returned to Aquincum and from there to Brigetio ([[Szőny]], Hungary) where he died suddenly in November.{{sfn|Curran|1998|p=86}}