JOVIANUS, FLAVIUS CLAUDIUS, Roman emperor from June 27, 363, to February 17, 364, was the son of the brave general Varronianus, and was born at Singidunum in Mcesia about 332. As captain of the guard (primes ordinis domesticorum) he accompanied Julian in his Persian expedition ; and on the day after that emperor's death, when the aged Sallust declined the purple, the voices of the army beyond the Tigris were united in Jovian's favour. It was perhaps the absence of any very invidious ability, no less than his father's reputation, that set Jovian on the throne. The new emperor's first care was to continue the retreat begun by Julian ; and he had with difficulty reached the rapid and well-nigh unpassable when overtures of peace were made by the Persian king Sapor II., who had not ceased to harass the Roman march. Jovianus was not in a position to command easy terms ; the famished and exhausted state of his army compelled his assent to a humiliating treaty, which gave up to the Persians the provinces of Arzanene, Corduene, Mexoene, Rehimene, and Zabdicene, which had been conquered by Galerius in 297, and Nisibis and other cities. From this time the Greek and Christian influence dates its decline in the trans-Euphrates regions. Jovian was anxious to reach Constantinople in order to establish his power ; but the news of the loyalty of the western legions gladdened him while still on the march through Asia Minor. After issuing a decree by which Christianity was restored as the state religion, though paganism was recognized, the emperor assumed the consulship at Ancyra, on January 1, 364, with his infant son as colleague. Within two months, on February 17, 364, Jovianus was found dead in his bed at Dadastana, a small town of Galatia. A surfeit of mushrooms or the fumes of a charcoal fire have been assigned as the causes of death. The suspicion of foul play is unsupported by evidence. He was succeeded by Valentinian and Valens, after an interregnum of ten clays.

Besides the ancient historians of the period, see Gibbon's Decline and Fall ; Le Beau's Bas-Empire ; Finlay's Greece under the Romans ; and the Abbe de la Bleterie's Histoire de JOViC77, Amsterdam, 1740. In Syriac literature Jovian (Iobinianos) became the hero of a Christian romance, published by George Hoffmann (Julianus der Abtriinnige, 1880). Compare the account of this work by Noldeke, Z. D. M. G., vol. xxviii.