William the Conqueror probably secured earlier. Papal sanction of the marriage appears to have required the founding of two monasteries in Caen – one by William and one by Matilda. The marriage was important in bolstering William's status, as Flanders was one of the more powerful French territories, with ties to the French royal house and to the German emperors. Contemporary writers considered the marriage, which produced four sons and five or six daughters, to be a success. No authentic portrait of William has been found; the contemporary depictions of him on the Bayeux Tapestry and on his seals and coins are conventional
William the Conqueror allegiance. William's exact motivation in ordering the survey is unclear, but it probably had several purposes, such as making a record of feudal obligations and justifying increased taxation. William left England towards the end of 1086. Following his arrival back on the continent he married his daughter Constance to Alan Fergant, the Duke of Brittany, in furtherance of his policy of seeking allies against the French kings. William's son Robert, still allied with the French king, appears to have been active in stirring up trouble, enough so that William led an expedition against the French Vexin in July 1087. While