We have occasional notices about Ammianus Marcellinus, rightly held to be the greatest pagan historian in the Latin language from late antiquity; these can be taken almost exclusively from his own works and from a letter (1063 Förster), which may perhaps have been sent to him at Rome by the orator Libanius in 392 AD.  The rhetorician, who names Marcellinus as the addressee of the letter, describes him as a native of Antioch, the capital of the province of Syria.  If one should maintain that the Marcellinus discussed by Libanius is to be identified with the historian Ammianus Marcellinus, therefore, the Antiochan origin of the latter would be secured; but many critics reject such an identification (e.g. Fornara, Bowersock, Barnes, contra Matthews, Sabbah), proposing instead Thessalonian, Alexandrian, or Phoenician origins for the historian.  He nevertheless must have resided at Antioch for a long time - from his youth, even if he was not a native - as is demonstrated by the frequent references to the city that are contained in his works, and his numerous connections to influential Antiochans (Kelly).  His date of birth is secure (330 AD), while the definition of the social status to which he belonged remains controversial. It was supposed for a long time that he was a member of the city’s curial class (Thompson, Viansino), but his extensive and refined bilingual education - and above all the fact that, already in 353, when, little more than an adulescens, he was commissioned by the emperor Constantius II as protector domesticus to the general staff of the eastern magister equitum, Ursicinus - lead us to maintain rather that he came from a family of the military or administrative élite of the empire (Barnes, Kelly).  He always remained faithful to Ursicinus, following him first to Nisibis in Mesopotamia, then, in 355, in Gaul against the usurper Silvanus, who was annihilated.  Having returned with his general to Amida in the east, he endured the siege and defeat by the Persians in 359, events that determined his subsequent exclusion from Ursicinus’ military assignments on the orders of the hated emperor Constantius II.  What happened to Ammianus after these changes of fortune is difficult to establish.  It is certain that in 363 he was in the retinue of the emperor Julian, when - having become Augustus after the death of Constantius - he promoted a new expedition in Persia.  The enterprise turned out to be doomed, since it not only entailed the unexpected death of the young emperor, but cost the Roman empire the loss of a full five provinces situated along the course of the Tigris.  At this point Ammianus probably retired to private life in Antioch, making trips to Egypt and Greece, evidence for which survives in the Res Gestae.  After the dreadful loss suffered by the emperor Valens at Adrianople in 378, he finally moved to Rome, where he probably remained for a long time, without ever pursuing the coveted office of senator (vir clarissimus), but surely taking the less high-sounding one of vir perfectissimus.  At Rome, as has been supposed (Barnes, Viansino, Kelly), he attached himself to the retinue of his compatriot Flavius Hypatius, who was named praefectus urbi and later Praetorian Prefect on the orders of the emperor Gratian; there the historian found a climate suitable to the definitive composition of his work, the Res gestae, which he chose to compose in Latin, in deference to Rome, despite perhaps having had a Greek education (Barnes, but contra, e.g. Fornara). [G. Vanotti; tr. C. L. Caterine].