Vegetius (Flavius Vegettos Renatus) was a celebrated military writer of the 4th century. Nothing is known of his life, station and military experience, save that in manuscripts he is called vir illustris and also comes.
His treatise, Epitoma rei militaris (also referred to as De Rei Militari), was dedicated to the reigning emperor (? Theodosius the Great). His sources, according to his own statement, were Cato, Cornelius Celsus, Frontinus, Paternus and the imperial constitutions of Augustus, Trajan and Hadrian. The book, which is a confused and unscientific compilation, has to be used with great caution, but is none the less invaluable to the student of the ancient art of war.
The first book is a plea for army reform, and vividly portrays the military decadence of the empire. The third contains a series of military maxims which were (rightly enough, considering the similarity in the military conditions of the two ages) the foundation of military learning, for every European commander, from William the Silent to Frederick the Great. When the French Revolution and the "nation in arms" came into history, we hear little more of Vegetius. Some of the maxims may be mentioned here as illustrating the principles of a war for limited political objects with which he deals:
In manuscript, Vegetius's work had a great vogue from the first, and its rules of siegecraft were much studied in the middle ages. It was translated into English, French and even Bulgarian before the invention of printing. The first printed editions are assigned to Utrecht (1473), Cologne (1476), Paris (1478), Rome (in Veieres de re mil. scriptores, 1487), and Pisa (1488). A German translation by Ludwig Hohenwang appeared at Ulm in 1475. Vegetius's position as the premier military critic was thenceforward assured. As late as the 18th century we find so eminent a soldier as Marshal Puysegur basing his own works on this acknowledged model, and the famous Prince de Ligne wrote "C'est un livre d'or." The fullest and most important modern edition is that of Karl Lang (Leipzig, 1869). An English version through the French was published by Caxton in 1489. For a detailed critical estimate of Vegetius's works and influence see Max Jahns, Gesch. der Kriegswissenschaften, i. 109-125.
An English translation of De Re Militari is available 
This entry was originally from the 1911 Encyclopedia Britannica.