Editing William the Conqueror (section)

=== Danish raids and rebellion ===
{{Further|Ely Rebellion}}
Although Sweyn had promised to leave England, he returned in early 1070, raiding along the Humber and East Anglia toward the [[Isle of Ely]], where he joined up with [[Hereward the Wake]], a local [[thegn]]. Hereward's forces captured and looted [[Peterborough Abbey]]. William was able to secure the departure of Sweyn and his fleet in 1070,<ref name=Douglas221>Douglas ''William the Conqueror'' pp. 221–222</ref> allowing him to return to the continent to deal with troubles in Maine, where the town of [[Le Mans]] had revolted in 1069. Another concern was the death of Count [[Baldwin VI of Flanders]] in July 1070, which led to a succession crisis as his widow, [[Richilde, Countess of Hainaut|Richilde]], was ruling for their two young sons, [[Arnulf III, Count of Flanders|Arnulf]] and [[Baldwin II, Count of Hainaut|Baldwin]]. Her rule was contested by [[Robert I, Count of Flanders|Robert]], Baldwin's brother. Richilde proposed marriage to William fitzOsbern, who was in Normandy, and fitzOsbern accepted. But after he was killed in February 1071 at the [[Battle of Cassel (1071)|Battle of Cassel]], Robert became count. He was opposed to King William's power on the continent, thus the Battle of Cassel upset the balance of power in northern France and cost William an important supporter.<ref name=Douglas223>Douglas ''William the Conqueror'' pp. 223–225</ref>

In 1071 William defeated the last rebellion of the north. Earl Edwin was betrayed by his own men and killed, while William built a causeway to subdue the Isle of Ely, where Hereward the Wake and Morcar were hiding. Hereward escaped, but Morcar was captured, deprived of his earldom, and imprisoned. In 1072 William invaded Scotland, defeating Malcolm, who had recently invaded the north of England. William and Malcolm agreed to peace by signing the [[Treaty of Abernethy]], and Malcolm probably gave up his son [[Duncan II of Scotland|Duncan]] as a hostage for the peace. Perhaps another stipulation of the treaty was the expulsion of Edgar the Ætheling from Malcolm's court.<ref name=Bates107>Bates ''William the Conqueror'' pp. 107–109</ref> William then turned his attention to the continent, returning to Normandy in early 1073 to deal with the invasion of Maine by [[Fulk le Rechin]], the [[Count of Anjou]]. With a swift campaign, William seized Le Mans from Fulk's forces, completing the campaign by 30 March 1073. This made William's power more secure in northern France, but the new count of Flanders accepted Edgar the Ætheling into his court. Robert also married his half-sister [[Bertha of Holland|Bertha]] to King [[Philip I of France]], who was opposed to Norman power.<ref name=Douglas228>Douglas ''William the Conqueror'' pp. 228–229</ref>

William returned to England to release his army from service in 1073 but quickly returned to Normandy, where he spent all of 1074.<ref name=Bates111>Bates ''William the Conqueror'' p. 111</ref> He left England in the hands of his supporters, including [[Richard fitzGilbert]] and William de Warenne,<ref name=Bates112 /> as well as Lanfranc.<ref name=Douglas231 /> William's ability to leave England for an entire year was a sign that he felt that his control of the kingdom was secure.<ref name=Bates112>Bates ''William the Conqueror'' p. 112</ref> While William was in Normandy, Edgar the Ætheling returned to Scotland from Flanders. The French king, seeking a focus for those opposed to William's power, proposed that Edgar be given the castle of [[Montreuil-sur-Mer]] on the Channel, which would have given Edgar a strategic advantage against William.<ref name=Douglas230 /> However, Edgar was forced to submit to William shortly thereafter, and he returned to William's court.<ref name=Bates111 />{{efn|Edgar remained at William's court until 1086 when he went to the [[Norman conquest of southern Italy|Norman principality in southern Italy]].<ref name=Bates111 />}} Philip, although thwarted in this attempt, turned his attentions to Brittany, leading to a revolt in 1075.<ref name=Douglas230>Douglas ''William the Conqueror'' pp. 230–231</ref>