the Church of the Holy Apostles adjoining the Mausoleum of Constantine in Constantinople was inaugurated. Valens's sister-in-law Marina Severa died in the same year, and Valentinian married Justina in her place. In autumn 371, Valens's second nephew, also 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 daughter Constantia at Trier. Constantia and Justina were both related to the house of Constantine, and the marriages linked the Valentinianic and Constantinian dynasties. Valens celebrated his decennalia on 29 March 374. In 375, the Baths of Carosa () – named for Valens's daughter Carosa – were inaugurated in Constantinople. Valens headed east after defeating the Goths, and began to prepare an attack on Persia, which threatened Armenia, in 375. Valens was distracted from his campaign against the Sasanians by wars against the Saracens and the Isaurians. Persian War: 373 As mentioned before, among Valens' reasons for contracting a hasty and not entirely favorable peace in 369 was the deteriorating state of affairs in the East. Jovian had surrendered Rome's much disputed claim to control over Armenia in 363, and Shapur II was eager to make good on this new opportunity. The Persian emperor began enticing Armenian lords over to his camp and eventually forced the defection of the Arsacid Armenian king, Arshak II (Arsaces II), whom he quickly arrested and incarcerated. The Armenian nobility responded by asking Valens to return Arshak's son, Pap. Valens agreed and sent Pap back to Armenia, but as these events took place during the war with the Goths he could not support him militarily. In response to the return of Pap, Shapur personally led an invasion force to seize control of Armenia. Pap and his followers took refuge in the mountains while Artaxata, the Armenian capital, and the city of Artogerassa along with several strongholds and castles were destroyed. Shapur sent a second invasion force to Caucasian Iberia to drive out the pro-Roman king Sauromaces II, and put his own appointee, Sauromaces's uncle Aspacures II on the throne. In the summer following his Gothic settlement, Valens sent his magister peditum (Master of Foot) Arinthaeus to support Pap. The following spring a force of twelve legions were sent under Terentius to regain Iberia and to garrison Armenia near Mount Npat. When Shapur counterattacked into Armenia in 371, his forces were bested by Valens'