Every act of defence begins, etymologically, with a blow. Latin dēfendere combined dē- (away) with -fendere (to strike), creating a verb that meant 'to strike away' — to repel an attacker by pushing back. The same -fendere root, paired with ob- (against), produced offendere, meaning 'to strike against,' giving English offend. Defence and offence are therefore twin concepts from the same Latin workshop, distinguished only by direction. Old French inherited defendre with its protective meaning intact but added a second sense: 'to forbid.' This dual meaning survives in modern French, where défense can mean either protection or prohibition. English took only the protective sense when it borrowed the word in the thirteenth century, though the legal system expanded it to include advocacy — defending a client means shielding them from accusation. The word fence, clipped from defence in the fourteenth century, shows how English shortens borrowed words into something barely recognisable.