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 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.