Stephen, King of England recognised Stephen's son Eustace as Duke of Normandy in exchange for Eustace giving fealty to the French king. Stephen was less successful, however, in regaining the Argentan province along the Normandy and Anjou border, which Geoffrey had taken at the end of 1135. Stephen formed an army to retake it, but the frictions between his Flemish mercenary forces led by William of Ypres and the local Norman barons resulted in a battle between the two halves of his army. The Norman forces then deserted the King, forcing Stephen to give up his campaign. Stephen agreed to another truce with Geoffrey,
Norman law of Normandy", originally "Summa de legibus Normanniae in curia laïcali") authored between 1235 and 1245. The Channel Islands remained part of the Duchy of Normandy until 1204 when King Philip II Augustus of France conquered the duchy from King John of England. The islands remained in the personal possession of the King of England and were described as being a Peculiar of the Crown. They retained the Norman customary law and developed it in parallel with continental Normandy and France, albeit with different evolutions. Norman law Norman law refers to the customary law of the Duchy of Normandy which developed