his then eight-year-old son to his troops on 24 August, as his co-augustus (), passing over the customary initial step of caesar. Junior augustus On 24 August 367 Gratian received from his father Valentinian the title of augustus. Valentinian, concerned with Gratian's age and inexperience, stated his son would assist commanders with upcoming campaigns. The magister peditum Merobaudes, together with the comes rei militaris Sebastianus, was sent by Valentinian to campaign against the Quadi. Around 370, Gratian's mother Marina Severa died and was interred in the Church of the Holy Apostles. Valentinian married again, wedding Justina. On 9 April 370, according to the Consularia Constantinopolitana and the Chronicon Paschale, the Church of the Holy Apostles adjoining the Mausoleum of Constantine in Constantinople was inaugurated. In autumn 371, Gratian's half brother, called Valentinian, was born to Justina, possibly at Augusta Treverorum (Trier). Gratian, who was then 15, was married in 374 to Constantius II's 13 year-old posthumous daughter Flavia Maxima Constantia at Trier. This marriage consolidated the dynastic link to the Constantinian dynasty, as had his father Valentinian I's second marriage to Justina, with her family connections. 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. Although at first unsuccessful, eventually 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. 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) laying waste to Alamannic territories. Gratian was awarded the victory titles of Germanicus Maximus and Alamannicus Maximus, and Francicus Maximus and Gothicus Maximus in 369. 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. It was