Ammianus Marcellinus is the last great Roman historian, whose writings stand comparison with those of Livy and Tacitus.
He was not a professional man of letters but an army office of Greek origin born at Antioch and contemporary with the events described in what remains of his work. He set himself the task of continuing the histories of Tacitus from A.D. 96 down to his own day. The first thirteen of his thirty-one books are lost; the remainder describe a period of only 25 years and the reigns of the emperors Constantius, Julian, Jovian, Valentinian and Valens, for which he is a prime authority. He was a pagan and an admirer of the apostate Julian, to whose career about the half the surviving books are devoted. Nevertheless, his treatment of Christianity is free from prejudice and his impartiality and good judgement have been generally acknowledged.