FOR the monks of Le Bec, as the above quotation shows, the requirement that a ruler should bring peace and do justice was paramount. In that sentiment, they were entirely in accord with the mainstream of medieval thought. Isidore of Seville had highlighted the need for kings to do justice, as had Alcuin, Wipo, and Fulbert of Chartres who, about a century before the monks of Le Bec wrote their act, had opined that the position of the king ‘makes him the fountain-head of justice’. Good rulers were supposed to bring peace and justice to their subjects, and those who were characterized as good rulers were made to perform that role by those who wrote about them. Thus, William of Poitiers might remark that ‘at last a most joyful day dawned splendidly for all who desired and eagerly awaited peace and justice. Our duke … was armed as a knight.’ Conversely, the construction of a negative image of Robert Curthose required that he should be unable to do justice, even though his military ability could be acknowledged.

The purpose of this chapter is to establish how the dukes went about maintaining the peace in their duchy and doing justice on those who broke it – ambitions which constitute two sides of the same coin. To pursue this objective, the chapter has been broken down into sections that divide justice into offences on one hand and disputes over property on the other.5 That division is not intended to suggest that contemporaries thought in more modern terms of criminal law and civil law, nor that the duke was supposed to act in one sphere but not the other. William of Poitiers, for one, made it clear that the duke was to do justice regarding all sorts of trespasses: ‘By his strict discipline (i.e. justice) and by his laws robbers, homicides, and evil-doers have been driven out of Normandy.’