Vegetius

Flavius Vegetius Renatus, known in English as Vegetius, was a Latin writer of the Later Roman Empire, most likely active in the late fourth and early fifth centuries. He matters because his treatise on the army was for centuries one of the few ancient manuals of Roman military institutions to survive intact, and it shaped how European commanders thought about war well into the early modern period.

Little is known about his life beyond what he reveals in his own writings. He does not present himself as a soldier but as a vir illustris et comes, a title that points to a position close to the imperial court. His name, Renatus, suggests he was a Christian, and he identifies himself as one at the start of his main work. His birth and death dates are unknown. The work can be dated after 383, because it refers to the Emperor Gratian as already deified. The earliest surviving copy bears a note by a scribe named Flavius Eutropius, written in Constantinople in 450.

Vegetius dedicated his writings to a reigning emperor he does not name clearly. Scholars disagree about whether he meant Theodosius I or Valentinian III, and some argue for a date around 430 to 435. He wrote two works: the Epitoma rei militaris, also known as De re militari, and the far less famous Digesta artis mulomedicinae, a veterinary treatise on diseases of horses and mules. The first brought him his lasting reputation.

The Epitoma is a practical handbook covering how to organise and fortify a camp, train troops, discipline unruly soldiers, march, fight battles, besiege towns and operate a navy. He explains that he first wrote Book I as a separate treatise and later, at the emperor's request, added the rest. His Latin is plain and direct, and he names as sources Cato, Celsus, Frontinus, Paternus and various imperial edicts. His tone is nostalgic. He laments the decline of the army in his own day and urges discipline and drill in place of relying on past glories.

In the Middle Ages and the Renaissance the work served as a reference for soldiers, and its detail made it valued by historians. It was copied widely, translated into several languages before printing arrived, and first printed in Utrecht in 1473. Its standing as a historical source declined from the fifteenth century, as ancient historians such as Polybius became available, and because critics faulted it for mixing institutions from different periods. Even so, it was still consulted in the eighteenth century. The saying 'if you want peace, prepare for war' is traditionally credited to him, though its original wording carries a slightly different sense.