William the Conqueror
The private wars continued into 1046. William's rule depended on the loyalty of his viscounts. By the fall of 1046 many of the families in lower Normandy began plotting to replace William as duke. Guy of Burgundy,  William's cousin, was sent to William's court in hopes he would do well there. William gave Guy castles at Brionne and Vernon. But Guy wasn't happy with this and decided he should rule Normandy himself. He became the leader of what was by now an open revolt. Two of William's viscounts joined Guy. William realized this was a serious threat and he asked King Henry for help. The French king came right away and brought a large army. The combined armies of Duke William and King Henry met the rebels at Val-es-Dunes. The rebels were defeated and Guy fled to his castle at Brionne. William kept the castle cut off from food or supplies until Guy gave up in 1049. The duke forgave his cousin, but Guy soon returned to Burgundy. William's victory at Val-es-Dunes gave him some control of Normandy.