After the death of the emperor Julian in his campaign against Persia in 363, his distant relative Procopius was the last surviving descendant of Constantine I.
[1] This link to the revered Constantinian dynasty made Procopius dangerous as a potential usurper, but the emperor Jovian allowed him to retire peacefully to his estates in Cappadocia.
In 365, while Valens was absent from Constantinople, Procopius emerged from exile, seizing control of the capital city and the adjoining provinces of Thrace and Bithynia.
[3] Valens reacted to the usurpation with despair, and the situation was saved by his generals, Salutius, Arintheus and Arbitio.
Valens's officers spoke to the rebellious soldiers, many of whom they had commanded in prior wars, and encouraged them to rejoin the legitimate emperor.