After Richard II. came Robert the Magnificent, who was called also Robert the Devil by the people. It was he, who from the walls of his castle at Falaise, if the legend be true, first saw Arlette the tanner's daughter who afterwards became the Mother of William the Bastard. As a boy William had a perilous life, and it is almost marvellous that he survived to change his appellation to that of "Conqueror." Robert the Magnificent had joined one of the crusades to the Holy Land when William was only seven years old, but before he left Normandy, he had made it known that he wished the boy to succeed him. For twenty years there was civil war between the greater barons and the supporters of the heir, but in the end William showed himself sufficiently strong to establish his power. He won a great battle at Val-es-Dunes where he had been met by the barons led by Guy of Burgundy, and, having taken some of the most formidable fortresses in the Duchy, he turned his attention to his foes outside with equal success. Soon after this William married Mathilda a daughter of Count Baldwin of Flanders, but although by this act he made peace with her country, William soon found himself in trouble with the church. Bishop Mauger, whom he had appointed to the See of Rouen, found fault with the marriage owing to its being within the forbidden degrees of relationship, and the papal sanction having been refused, William only obtained his wishes through the agency of Lanfranc. All his life William appears to have set a stern example of purity in family life, and his relations with the church, from this time to his death, seem to have been most friendly. It was largely due to his religious life as well as the support he gave to the monasteries that William was able to give the colour of a religious crusade to his project for invading England. Harold had slighted the sacredness of the holy relics of the saints of Normandy, and William was to show England that their king's action was not to pass unpunished. In this way the Norman host that assembled at Dives, while the great fleet was being prepared, included many who came from outside William's dominions. After the whole of England had been completely subjugated William had his time and attention largely taken up with affairs in Normandy. His son Robert was soon in open rebellion, and assisted by the French King, Philip I., Robert brought about the death of his father, for it was while devastating a portion of French territory that William received the injury which resulted in his death. Robert then became Duke of Normandy, and there followed those sanguinary quarrels between the three brothers William Rufus, King of England, Henry Beauclerc and Robert. Finally, after his return from Palestine, Robert came to England to endeavour to make peace with his younger brother Henry, who was now king, but the quarrel was not to be settled in this way. Henry, determined to add Normandy to the English crown, crossed the channel with a large army and defeated his brother at Tinchebrai in 1106. With the accession of Stephen to the English throne in 1135, came the long struggle between that king and Maud. When Henry II. married Eleanor of Aquitaine, not only that great province but also Maine and Anjou came under his sway, so that for a time Normandy was only a portion of the huge section of France belonging to the English Crown. During his long reign Henry spent much time in Normandy, and Argentan and Avranches are memorable in connection with the tragedy of Thomas a Becket. During the absence of Richard Coeur-de-Lion in Palestine John became exceedingly friendly with Philip Augustus, the French King, but when Richard was dead he found cause to quarrel with the new English king and, after the fall of the Chateau Gaillard, John soon discovered that he had lost the Duchy of Normandy and had earned for himself the name of "Lackland."
From this time, namely, the commencement of the thirteenth century, Normandy belonged to the crown of France although English armies were, until 1450, in frequent occupation of the larger towns and fortresses.