(Προκόπιος), Roman emperor in the East, through rebellion, from A. D. 363 to 366. According to all probability, he was a relation of the emperor Julian through Basilina, the mother of that emperor, and the second wife of Constantius Consul, who was the youngest son of Constantius Chlorus. [See the genealogical table Vol. I. p. 832.] Procopius was a native of Cilicia, where he was born about A. D. 365. Constantius II. made him his secretary, and employed him in the field as tribune. The emperor Julian created him comes, and appointed him commander in Mesopotamia, when he set out against Persia in A. D. 363. It was then said that Julian had advised him to assume the purple, or manifested a wish that he should be his successor in case he should lose his life in the projected expedition, and this saying afterwards found many believers, to the great advantage of Procopius. However, it was Jovian who succeeded Julian, in 363, and by him Procopius was charged with conducting the body of the fallen hero to Tarsus. Aware that Jovian entertained suspicions against him, or, perhaps, in order to carry out schemes which, at that period, nobody expected, Procopius went to Caesareia in Cappadocia, instead of returning to the imperial quarters. This step was sufficient to rouse the suspicions of Jovian, whatever might have been his previous disposition, and some troops were despatched to seize the fugitive, who, however, deceived his pursuers, and escaped with his family to Tauris. Afraid of being betrayed by the barbarians, he soon left that country and returned to Asia Minor; a dangerous step, which, however, throws some light on his secret plans. During some time he wandered from place to place, and his return having been discovered by Valentinian and Valens, the successors of Jovian (364), he hid himself in the mountains, till at last he found refuge at the house of the senator Strategius, who lived near Chalcedon. Strategius became a confidant of the ambitious schemes of Procopius, who found further adherents among the numerous adversaries of Valens in Constantinople, whither the fugitive general often proceeded on secret visits. The eunuch Eugenius became one of the principal promoters of the plans of Procopius, which were now manifestly those of deposing Valens, and making himself master of the East. The plot broke out in 365, and owing to his numerous partisans and his own artifices, the people of Constantinople proclaimed him emperor on the 28th of September of that year. The emperor Valens was at that period staying at Caesareia in Cappadocia, but was soon informed of the rebellion, and prepared for effective resistance. Meanwhile, Procopius set out for Asia Minor with a well-disciplined army, advanced as far as the Sangarius, and, through a bold stratagem, caused an imperial body, which defended the passage of that river, to desert their master, and join his own army. However, Valens advanced in his turn, and laid siege to Chalcedon, but was defeated under its walls, and obliged to retreat into Phrygia; Marcellus, a general of Procopius, took the important town of Cyzicus, and Procopius became master of Bithynia; a series of successes which turned his mind, made him haughty, and caused him more adversaries than adherents. The war was renewed with vigour in the spring of the following year 366, but to the great disadvantage of Procopius, whose army, commanded by the fugitive Persian prince, Hormisdas, was totally defeated by the celebrated general Arbetion. Soon afterwards, on the 27th of May, 366, another battle was fought at Nacolia, in Phrygia, the two rivals commanding their armies in person, and it ended in the rout of the rebels. Procopius fled, accompanied by a few attendants, with whom he wandered some days in the mountains, when they treacherously seized him, and delivered him into the hands of Valens, by whose order he was immediately put to death. Socrates says that Procopius suffered death by being tied to two trees forcibly bent together, which, on snapping asunder, tore the body of the unfortunate man to pieces. The cruel conduct of Valens against the partisans of Procopius belongs to the history of the former. There are gold and silver coins of Procopius extant, the former being extremely rare, according to Eckhel. (Amm. Marc. 26.6; Zosim. lib. iv.; Themist. Orat. 7; Socrat. 4.3, &c. ; Philostorg. 9.5; Eckhel, vol. viii. pp. 156, 157.)