Roman emperor (A. D. 363-364), was the son of the Comes Varronianus, one of the most distinguished generals of his time, who had retired from public life when the accession of his son took place. Jovianus was primus ordinis domesticorum, or captain of the lifeguards of the emperor Julian, and accompanied him on his unhappy campaign against the Persians. Julian having been slain on the field of battle, on the 26th of June, A. D. 363, and the election of another emperor being urgent, on account of the danger in which the Roman army was placed, the choice of the leaders fell first upon their veteran brother Sallustius Secundus, who, however, dedined the honour, and proposed Jovian. The merits of his father more than his own induced the Roman generals to follow the advice of their colleague, and Jovian was proclaimed emperor on the day after the death of Julian. He immediately professed himself to be a Christian. The principal and most difficult task of the new emperor was to lead his army back into the old Roman territories. No sooner had he begun his retreat, than Sapor, the Persian king, who had been informed of the death of Julian, made a general attack upon the Romans. Jovian won the day, continued his retreat under constant attacks, and at last reached the Tigris, but was unable with all his efforts to cross that broad, deep, and rapid river in presence of the Persian army. In this extremity he listened to the propositions of Sapor, who was afraid to rouse the despair of the Romans. After four days' negotiations he purchased the safety of his army by giving up to the Persian king the five provinces, or rather districts, beyond the Tigris, which Galerius had united to the Roman empire in A. D. 297, viz. Arzanene, Moxoene, Zabdicene, Rehimene and Corduene, as well as Nisibis and several other fortresses in Mesopotamia. Great blame has been thrown upon Jovian for having made such a disgraceful peace; but the circumstances in which he was placed rendered it necessary, and he was, moreover, anxious to secure his crown, and establish his authority in the western provinces. He had no sooner crossed the Tigris than he despatched officers to the West, investing his father-in-law Lucillianus with the supreme command in Italy, and Malaricus with that in Gaul. On the western banks of the Tigris he was joined by Procopius with the troops stationed in Mesopotamia, and being now out of danger, he devoted some time to administrative and legislative business. His chief measure was the celebrated edict, by which he placed the Christian religion on a legal basis, and thus put an end to the persecutions to which the Christians had been exposed during the short reign of Julian. The heathens were, however, equally protected, and no superiority was allowed to the one over the other. The different sectaries assailed him with petitions to help them against each other, but he declined interfering, and referred then to the decision of a general council ; and the Arians showing themselves most troublesome, he gave them to understand that impartiality was the first duty of an emperor. His friend Athanasins was restored to his see at Alexandria. After having abandoned Nisibis to the Persians, he marched through Edessa, Antioch, Tarsus, and Tyana in Cappadocia, where he learnt that Malaricus having declined the command of Gaul, Lucillianus had hastened thither from Italy, and had been slain in a riot by the soldiers, but that the army had been restored to obedience by Jovinus. From Tyana Jovian pursued his march to Constantinople, in spite of an unusually severe winter. On the 1st of January, 364, he celebrated at Ancyra his promotion to the consulship, taking as colleague his infant son Varronianus, whom he called nobilissimus on the occasion. Having arrived at Dadastana, a small town in Galatia, on the borders of Bithynia, he indulged in a hearty supper and copious libations of wine, and endeavoured to obtain sound repose in an apartment which had lately been whitewashed, by ordering burning charcoals to be placed in the damp room. On the following morning (17th of February, 364) he was found dead in his bed. His death is ascribed to various causes--to intemperance, the coal-gas, and the poison of an assassin. It is possible, though not probable, that he died a violent death, to which Ammianus Marcellinus (25.10) seems to allude when he compares his death with that of Aemilianus Scipio. (Amm. Marc. 25.5-10; Eutrop. 10.17, 18; Zosim. iii. p. 190, &c., ed. Paris; Zonar. vol. ii. pp. 28, 29, ed. Paris; Oros. 7.31; Sozomen. 6.3; Philostorg. 8.5; Agathias, iv. p. 135, &c., ed. Paris; Themistius dwells upon the history of Jovian in several orations, especially Or. 5 and 7, and bestows all the praise on him which we might expect from a panegyrist; De la Bléterie, Histoire de Jovien, Amsterd. 1740, the best work on the subject.)