The Rebellion of 1088 occurred after the death of William the Conqueror and concerned the division of lands in the Kingdom of England and the Duchy of Normandy between his two sons William Rufus and Robert Curthose. Hostilities lasted from 3 to 6 months starting around Easter of 1088. Background William on his deathbed in 1087 decided how his sons would inherit the lands of his native Normandy and recently conquered England. His eldest son Robert was made Duke of Normandy and his third eldest son (second eldest surviving son) William Rufus was made King of England. This came to pass on William's death. The division of William the Conqueror's lands into two parts presented a dilemma for those nobles who held land on both sides of the English Channel. Since the younger William and his brother Robert were natural rivals, these nobles worried that they could not hope to please both of their lords, and thus ran the risk of losing the favour of one ruler or the other, or both. The only solution, as they saw it, was to unite England and Normandy once more under one ruler. The pursuit of this aim led them to revolt against William in favour of Robert, under the leadership of the powerful Bishop Odo of Bayeux, who was a half-brother of William the Conqueror. The rebels, led by William the Conqueror's half-brothers Odo of Bayeux and Robert, Count of Mortain, with Odo the stronger of the two and the leader, decided to band together to dispose of young King William II and reunite Normandy and England under a single ruler, Robert. Among King William's initial supporters were all the bishops of England, a few major magnates including Alan Rufus (in the east of England north of London up to Yorkshire), William de Warenne, 1st Earl of Surrey (from Sussex to Yorkshire) and Hugh of Avranches (in the west, around Cheshire, and in Lincolnshire),[6] and lesser tenants-in-chief such as Robert Fitzhamon and Walter D'Aincourt. However, the rebels' ranks were made up many of the most powerful barons in England: of the ten largest baronial landholders in the Domesday Book, six were counted amongst the rebels. They were spread far and wide geographically from Kent, controlled by Bishop Odo, to Northumberland, controlled by Robert de Mowbray, to Gloucestershire and Somerset under Geoffrey de Montbray (Bishop of Coutances), to Norfolk with Roger Bigod, through