Vegetius

Publius Flavius Vegetius Renatus was a writer of the Later Roman Empire whose Epitoma rei militaris (also known as De re militari) is the only intact ancient manual of Roman military institutions. From it descends the famous adage Si vis pacem, para bellum — Vegetius’s own words were “Igitur qui desiderat pacem, praeparet bellum” (“therefore let him who desires peace prepare for war”). That maxim, not anything by Sun Tzu, is the true ancestor of the popular quote.