De re militari  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") 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. Vegetius' dates are not known, nor are the circumstances under which the work was revised. The year 450 is taken as the latest possible time the work could have been written, assuming he did all seven revisions in just a few years. The initial date of the window is established by Vegetius' own statement that he wrote covering the time "usque ad tempus divi Gratiani", "up to the time of the divine Gratian." As emperors did not become gods generally until they died, the statement sets the initial possible date ("terminus post quem") at 383, the year Gratian died.