The Roman History of Ammianus Marcellinus by Ammianus Marcellinus; Translated by C. D. Yonge. Ammianus Marcellinus (325/330-after 391) was a fourth-century Roman soldier and historian. History during the Reigns of the Emperors Constantius, Julian, Jovianus, Valentinian, and Valens. Of Ammianus Marcellinus, the writer of the following History, we know very little more than what can be collected...