The historian Ammianus Marcellinus (c. 330–c. 395 CE) was born in the eastern part of the empire, probably in Antioch. He served in the elite cavalry corps of the protectores domestici on the staff of general Ursicinus. In 355 CE he travelled in this capacity from the eastern part of the empire to the court of Constantius II Augustus at Milan, who sent Ursicinus on a mission to Cologne in order to liquidate the usurper Silvanus. Between 357 and 359 CE, Am…