Sean McGlynn investigates the reality of medieval warfare. For all the talk of chivalry, medieval warfare routinely involved acts which we would consider war crimes. Lands laid waste, civilians slaughtered, prisoners massacred: this was standard fare justified by tradition and practical military necessity. It was unbelievably barbaric, but seldom uncontrolled. Such acts of atrocity were calculated, hideous cruelties inflicted in order to achieve a specific end. Sean McGlynn examines the battles of Acre and Agincourt, sieges like Beziers, Lincoln, Jerusalem and Limoges as well as the infamous chevauchees of the Hundred Years War that devastated great swathes of France. He reveals how these grisly affairs form the origin of accepted 'rules of war', codes of conduct that are today being enforced in the International Court of Justice in the Hague.