cooperation between the Limitanei (border regiments) of Mesopotamia and Osrhoene under Ursicinus' command and the comitatus (field army) of Sabinianus. While on a mission near Nisibis, Ammianus spotted a Persian patrol which was about to try and capture Ursicinus, he was able to warn his commander in time. In an attempt to locate the Persian Royal Army Ursicinus sent Ammianus to Jovinianus, the semi-independent governor of Corduene, and a friend of Ursicinus. Ammianus successfully located the Persian main body and reported his findings to Ursicinus. After his mission in Corduene, Ammianus accompanied his commander when the latter rode out from his headquarters at Amida on a mission to make sure the bridges across the Euphrates were demolished. They were attacked by the Persian vanguard who had made a night march in an attempt to catch the Romans at Amida off guard. After a protracted cavalry battle the Romans were scattered, Ursicinus evaded capture and fled to Melitene while Ammianus barely made it back to Amida with a wounded comrade. The Persians started to besiege the city. When it fell Ammianus barely escaped with his life. When Ursicinus was dismissed from his military post by Constantius, Ammianus too seems to have retired from the military; however, reevaluation of his participation in Julian's Persian campaign has led modern scholarship to suggest that he continued his service but did not for some reason include the period in his history. He accompanied Julian, for whom he expresses enthusiastic admiration, in his campaigns against the Alamanni and the Sassanids. After Julian's death, Ammianus accompanied the retreat of the new emperor, Jovian, as far as Antioch. He was residing in Antioch in 372 when a certain Theodorus was thought to have been identified the successor to the emperor Valens by divination. Speaking as an alleged eyewitness, Marcellinus recounts how Theodorus and several others were made to confess their deceit through the use of torture, and cruelly punished. He eventually settled in Rome and began the Res Gestae. The precise year of his death is unknown, but scholarly consensus places it somewhere between 392 and 400 at the latest. Modern scholarship generally describes Ammianus as a pagan who was tolerant of Christianity. Marcellinus writes of Christianity as being a "plain and simple" religion that demands only what is just and mild, and when he condemns the actions of Christians, he does not do so on the basis