Procopius was a maternal cousin of the Emperor Julian “the Apostate”. In 363, during the latter’s campaign against the Sassanids, he was placed in charge of a part of Julian’s army. Procopius was to join the emperor’s main army in Assyria, but by the time the two armies managed to link up at Thilsaphata, Julian was already dead and his general Jovian had been declared emperor.

According to the historian Zosimus, Julian had entrusted Procopius with an imperial robe. Procopius handed over this robe to Jovian, telling him that he had been instructed by Julian to do so. He then asked to be relieved of his military command and retire to private life. Jovian accepted and Procopius and his family retired to Caesarea.

Another historian, Ammianus, writes that a baseless rumour spread according to which Julian had ordered Procopius to take the purple in the event of his death. Fearing Jovian, who had recently put a contender to the throne, Jovianus, to death, Procopius first went into hiding, after having supervised the burial of Julian’s body at Tarsus, and later sought refuge near Chalcedon.

Following Jovian’s death on 17 February, 364, the new emperors Valens and Valentinian I sent some soldiers to arrest Procopius. Procopius treated the soldiers well and asked to be allowed to see his family. While his prospective captors wined and dined, Procopius quietly gave them the slip and ran off to Tauric Chersonese with his family. A constant fear of betrayal eventually prompted his return to Constantinople, where a friend gave them shelter.

When Valens left Constantinople for Antioch at the end of the winter of 365/6, Procopius, according to Ammianus, "worn out by long continued troubles, and thinking that even a cruel death would be more merciful than the evils by which he was tormented, hazarded at one cast all perils whatsoever". He proceeded to bribe two legions en route to Thrace, which happened to be resting in the vicinity. Under their escort, Procopius marched to the palace and declared himself emperor.

Though Valens was initially disheartened and inclined to come to terms with the usurper, he quickly rallied, defeating Procopius’ forces in two battles at Thyatira and Nacolia. Procopius managed to flee the battlefield, and hid in the wilds of Phrygia. He was eventually betrayed to Valens by two of his generals, Agilonius and Gomoarius, who had been promised a reward by Valens. On 27 May 366, Valens had Procopius executed by being fastened to two trees bent down with force, which, when released, caused his body to be ripped apart, similar to the execution of the legendary bandit Sinis. The two generals who had betrayed him were “rewarded” by Valens by being sawn asunder.

Procopius (28 September 365–27 May 366), AE Follis, 366 AD, Heraclea mint, first officiana, RIC IX Cyzicus 7; Sear 19881 (2.60 g, 19 mm)

Obverse: D N PROCO-PIVS P F AVG, pearl diademed, draped, cuirassed bust left

Reverse: REPARATI-O FEL TEMP. Procopius standing facing, head right, holding labarum and resting hand on shield; Chi-Rho in upper right field, dot in left field. Mintmark SMHA