Jovian

Jovian (Latin: Jovianus; Greek: Ἰοβιανός Iobianós; 331 – 17 February 364) was Roman emperor from June 363 to February 364. As part of the imperial bodyguard, he accompanied Julian on his Persian expedition. Julian was killed in battle, and the exhausted and ill-provisioned Roman army declared Jovian his successor. Unable to cross the Tigris, Jovian made peace with the Sasanian Empire on humiliating terms. He spent the rest of his seven-month reign traveling back towards Constantinople, but died at Dadastana without reaching the capital city.

Jovian was a Christian, whose accession ended the imperial endorsement of polytheism briefly revived under Julian; during a stop in Edessa he received petitions from bishops over doctrinal issues. He was also the third-to-last emperor to govern the empire as a single polity, and the last to do so for the whole of his reign. From his successor Valentinian I to the fall of the Western Roman Empire, all subsequent administrations involved co-emperors governing a territory split into jurisdictions of the East and West.