De re militari (Latin "Concerning Military Matters"), also known as Epitoma rei militaris, is a work by the Publius Flavius Vegetius Renatus. The book casts light on the Roman warfare and military principles. It gives a presentation of the methods and practices in use during the height of the Roman Empire. The text was written in the 5th century. According to Vegetius, things like training of soldiers as a disciplined force, orderly strategy, maintenance of supply lines and logistics, quality leadership, and use of tactics and even deceitwere all extremely important to ensure advantage over the opposition. He also stressed the selection of good soldiers and recommended hard training of at least four months before the soldier was accepted into the ranks.