De Re Militari

De Re Militari
"Concerning Military Matters"
Edition bound in goatskin, Republic of Venice, c.1486–1501
Also known as	Epitoma rei militaris, Epitoma institutorum rei militaris
Author(s)	Publius Flavius Vegetius Renatus, though the work was revised a number of times afterwards
Dedicated to	Emperor Valentinian
Language	Late Latin
Date	383 x 450, possibly in the reign of Theodosius I (r. 378-395)
First printed edition	Epithoma rei militaris. Utrecht, 1473.
Genre	military treatise
Subject	military leadership, training, discipline, tactics, logistics, organisation of the army, etc.
Period covered	purports to describe the army in the heydays of the Roman Empire
Sources	include Cato the Elder, Cornelius Celsus, Frontinus, Paternus, Imperial Constitutions of Augustus, Trajan, Hadrian

De Re Militari (Latin "Concerning Military Matters"), also Epitoma Rei Militaris, is a treatise by the late Latin writer Publius Flavius Vegetius Renatus about Roman warfare and military principles as a presentation of methods and practices in use during the height of Rome's power, and responsible for that power. The extant text dates to the 5th century.

Vegetius emphasized things such as training of soldiers as a disciplined force, orderly strategy, maintenance of supply lines and logistics, quality leadership and use of tactics and even deceit to ensure advantage over the opposition. He was concerned about selection of good soldiers and recommended hard training of at least four months before the soldier was accepted into the ranks. The leader of the army (dux or duke) had to take care of the men under his command and keep himself informed about the movements of the enemy to gain advantage in the battle.

De Re Militari became a military guide in the Middle Ages. Even after the introduction of gunpowder to Europe, it was carried by general officers and their staffs as a field guide to methods. Friends and subordinates customarily presented embellished copies as gifts to leaders. It went on into the 18th and 19th centuries as a source of policy and strategy to the major states of Europe. In that sense De Re Militari is a projection of Roman civilization into modern times and a continuation of its influence on its cultural descendants.

The author of De Re Militari was Publius Flavius Vegetius Renatus, who lived in the late 4th century and possibly the early 5th century. The name of the work has a number of variants, including Epitoma Rei Militaris, but there are other problems with accepting it at face value as the verbatim work of Vegetius. Some of the manuscripts have a note that the text was revised for the 7th time in Constantinople in the consulate of Valentinian, who must have been Valentinian III, reigning 425-455.