The latest event alluded to in his Epitoma rei militaris is the death of the Emperor Gratian (383); the earliest attestation of this work is a subscriptio by one Flavius Eutropius, writing in Constantinople in the year 450, which appears in one of two families of manuscripts, suggesting that a bifurcation of the manuscript tradition had already occurred. Despite Eutropius' location in Constantinople, the scholarly consensus is that Vegetius wrote in the Western Empire. Vegetius dedicates his work to the reigning emperor, who is identified as Theodosius, ad Theodosium imperatorem, in the manuscript family that was not edited in 450; the identity is disputed: some scholars identify him with Theodosius the Great, while others follow Otto Seeck and identify him with the later Valentinian III, dating the work 430-35.
The first book is a plea for army reform; it vividly portrays the military decadence of the Late Roman Empire. Vegetius also describes in detail the organisation training and equipment of the army of the early 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 objectives with which he deals:
These are maxims that have guided the leaders of professional armies for most of recorded history, as witness the Chinese generals Sun Tzu and Wu. His "seven normal dispositions for battle," once in honor among European students of the art of war, are equally useful if applied to more modern conditions. His book on siegecraft is important as containing the best description of Late Empire and Medieval siegecraft. From it, among other things, we learn details of the siege engine called the onager, which afterwards played a great part in sieges, until the development of modern cannonry. The fifth book is an account of the materiel and personnel of the Roman navy.
The author of the 1911 Encyclopaedia Britannica article states that "In manuscript, Vegetius's work had a great vogue from its first advent. Its rules of siegecraft were much studied in the Middle Ages." N.P. Milner observes that it was "one of the most popular Latin technical works from Antiquity, rivalling the elder Pliny's Natural History in the number of surviving copies dating from before AD 1300. It was translated into English, French (by Jean de Meun and others), Italian (by the Florentine judge Bono Giamboni and others), Catalan, Spanish, Czech, and Yiddish before the invention of printing. The first printed editions are ascribed to Utrecht (1473), Cologne (1476), Paris (1478), Rome (in Veteres de re mil. scriptores, 1487), and Pisa (1488). A German translation by Ludwig Hohenwang appeared at Ulm in 1475.
However, from that point Vegetius's position as the premier military authority began to decline, as ancient historians such as Polybius became available. Niccolò Machiavelli attempted to address Vegetius's defects in his L'arte della Guerra (Florence, 1521), with heavy use of Polybius, Frontinus and Livy, but Justus Lipsius's accusation that he confused the institutions of diverse periods of the Roman Empire and G. Stewechius' opinion that the survival of Vegetius' work led to the loss of his named sources were more typical of the late Renaissance. While 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". In Milner's words, Vegetius' work suffered "a long period of deepening neglect".
The most reliable modern edition is that of Michael D. Reeve (Oxford, 2004). An early English version (via French) was published by Caxton in 1489. For a detailed critical estimate of Vegetius's works and influence, see Max Jahns, Geschiche der Kriegswissenschaften, i. 109-125.
Vegetius is keen to stress the shortcomings of the Roman Army in his lifetime. In order to do this he eulogises the Army of the early Empire. In particular he stresses the high standard of the recruits and the excellence of the training and the officer corps. In reality, Vegetius probably describes an ideal rather than the reality. The Army of the early Empire was a formidable fighting force but it probably was not in its entirety quite as good as Vegetius describes. In particular, the five foot eight minimum height limit would have excluded the vast majority of the working classes in Roman times.
An English translation of Vegetius, with introduction, was recently published by Liverpool University Press:
Vegetius: Epitome of Military Science. Trans. N.P. Milner. Liverpool: Liverpool University Press, 1993 and 1996.
A translation in Dutch was published by Fik Meijer, entitled: Vegetius, 'Het Romeinse leger' ('The Roman Army' (Polak/Van gennep Publishers, Amsterdam, 2004)
An English translation of De Re Militari by Lieutenant John Clarke (1767) is available online