Origins
The word 'war' reveals that the Germanic peoples who coined its ancestor understood armed conflict not primarily as violence but as disorder — the confusion and breakdown of social bonds. It enters English around 1050 from Old North French 'werre' (war, conflict, strife), from Frankish *werra (confusion, discord, quarrel), from Proto-Germanic *werzō (confusion, mixture, a mixing-up), possibly from PIE *wers- (to confuse, to mix up).
The Frankish word *werra was borrowed into French very early — during the period of Frankish dominance over Gaul (5th–9th centuries) — and replaced the Latin word 'bellum' (war) in everyday Gallo-Romance speech. The Latin word survives only in learned English borrowings: 'belligerent,' 'bellicose,' 'antebellum,' 'rebellion.' For the colloquial vocabulary of conflict, the Germanic word won.
Proto-Indo-European Roots
French dialectal variation created two distinct pathways for the same word. In Old North French (the Norman dialect), *werra became 'werre,' with the Germanic /w/ preserved. This is the form that entered English after the Norman Conquest, giving 'war,' 'warrior,' 'warfare.' In Central French (the Parisian dialect), the initial /w/ shifted to /gw/ and then /g/, producing 'guerre.' This Central French form entered Spanish as 'guerra' and Italian as 'guerra,' and the Spanish diminutive 'guerrilla' (little war) re-entered English in the early nineteenth century to describe the irregular warfare practiced by Spanish partisans against Napoleon's armies. So 'war' and 'guerrilla' are the same word, separated by dialect and diminutive.
The original meaning of 'confusion' or 'disorder' is significant. Many ancient cultures named war not for its violence but for its social consequences — the disruption of peace, the dissolution of order, the mixing-up of what should be kept separate. The Proto-Germanic *werzō (confusion, mixture) names exactly this: war as a state where the boundaries that organize society collapse. This is conceptually different from Latin 'bellum' (war, from older *duellum, a contest between two), which frames war as a duel — a structured, almost athletic competition. The Germanic understanding was darker: war is chaos.