Christmas Day, 1066, in London. He made arrangements for the governance of England in early 1067 before returning to Normandy. Several unsuccessful rebellions followed, but William's hold was mostly secure on England by 1075, allowing him to spend the greater part of his reign in continental Europe. William's final years were marked by difficulties in his continental domains, troubles with his son, Robert, and threatened invasions of England by the Danes. In 1086, he ordered the compilation of the Domesday Book, a survey listing all the land-holdings in England along with their pre-Conquest and current holders. He died in September 1087 while leading a campaign in northern France, and was buried in Caen. His reign in England was marked by the construction of castles, settling a new Norman nobility on the land, and change in the composition of the English clergy. He did not try to integrate his domains into one empire but continued to administer each part separately. His lands were divided after his death: Normandy went to Robert, and England went to his second surviving son, William Rufus. Background Norsemen first began raiding in what became Normandy in the late 8th century. Permanent Scandinavian settlement occurred before 911, when Rollo, one of the Viking leaders, and King Charles the Simple of France reached an agreement ceding the county of Rouen to Rollo. The lands around Rouen became the core of the later duchy of Normandy. Normandy may have been used as a base when Scandinavian attacks on England were renewed at the end of the 10th century, which would have worsened relations between England and Normandy. In an effort to improve matters, King Æthelred the Unready took Emma, sister of Richard II, Duke of Normandy, as his second wife in 1002. Danish raids on England continued, and Æthelred sought help from Richard, taking refuge in Normandy in 1013 when King Swein I of Denmark drove Æthelred and his family from England. Swein's death in 1014 allowed Æthelred to return home, but Swein's son Cnut contested Æthelred's return. Æthelred died unexpectedly in 1016, and Cnut became king of England. Æthelred and Emma's two sons, Edward and Alfred, went into exile in Normandy while their mother, Emma, became Cnut's second wife. After Cnut's death in 1035, the English throne fell to Harold Harefoot, his son by his first wife, while Harthacnut, his son by Emma, became king in Denmark. England