Ammianus Marcellinus (c. 330 - after 391) is the preeminent historian of the Late Roman Empire, whose extant work forms the most important narrative we possess on the Fourth Century A.D. Born of genteel extraction in a Greek-speaking part of the empire, Ammianus served in the army in campaigns ranging form Gaul to Persia before settling in Rome and beginning his literary carreer. Besides shedding light on many events from the reign of Constantius to the calamitous defeat at Adrianople - including striking portraits of emperors Julian and Valentinian - his work offers as well a compelling description of Late Roman society.