Ammianus Marcellinus

Born around 330 CE, likely in Antioch, Ammianus Marcellinus entered imperial service as a protector domesticus under the general Ursicinus. He marched through the eastern wars of Constantius II and later served in Julian’s Persian expedition. He survived the terrible siege of Amida (359), where he watched Sasanian siegecraft press Roman defenses and where the sounds and shocks of war imprinted themselves on a soldier’s memory. After years of service, he settled into letters, composing his Res Gestae in polished Latin for audiences in Rome and beyond.

Ammianus’s eye is that of a campaigner who knows the value of spade and sinew. He describes battering rams suspended and swung like great pendulums, their steady rhythm turning stone to rubble; mines and countermines where earth and air smelled of damp clay and oil; and the use of mobile towers—sometimes borne on ships or river barges—to dominate walls from the waterline during assaults on fortified river towns. He counts out the routines that enable such efforts: camps thrown up day by day with ditches and palisades, engines protected by sheds, and work gangs rotated under shields against arrows and fire. In his pages, fourth-century operations on the Danube, in Mesopotamia, and around cities like Amida and Aquileia show Roman forces adapting old methods to new theaters—floating bridges, ship-borne platforms, and entrenched lines that still disciplined battlefields.

He faced danger and disillusion in equal measure. As an officer attached to commanders who fell in and out of favor, Ammianus knew the bite of court politics as well as the spear. He wrote with a moralist’s temper—praising discipline, scorning luxury, and treating preparedness as a civic virtue. The man who endured the chaos of sieges also marveled at their mechanics, explaining how order under fire could still be imposed by habit and hierarchy. If he lacked the imperial access of earlier historians, he compensated with lived detail and a soldier’s sense of what mattered.

As the last great Latin historian of Rome to cover the empire’s frontiers from 96 to 378, Ammianus preserves the continuity of Roman engineering practice when other sources thin. For this timeline, he is the late echo of earlier routines: his rams still swing, his trenches still fill, his towers still climb—some even from the decks of ships. He proves that the Roman habit of building its way out of peril persisted into an age of different foes and harsher margins, giving commanders the same tools—time, reach, control—that had once won them the world.