http://en.wikipedia.org/wiki/Robert_of_Bellême

Robert de Bellême, 3rd Earl of Shrewsbury , also spelled Belleme or Belesme, was an Anglo-Norman nobleman, and one of the most prominent figures in the competition for the succession to England and Normandy between the sons of William the Conqueror. He also known as Robert II de Montgommery, seigneur of Bellême.
He was the eldest son of Roger of Montgomery, 1st Earl of Shrewsbury and Mabel of Bellême.

Early life
Robert's first notable act, as a young man, was to take part in the 1077 revolt of the young Robert Curthose against William the Conqueror, an act he shared with many other Norman nobles of his generation. The rebellion was put down, and the participants pardoned. William did require that ducal garrisons be placed in the important baronial castles, which would make future rebellion much more difficult.
Robert's mother Mabel was killed in 1082, whereupon Robert inherited her property which stretched across the hilly border region between Normandy and Maine. It is due to this early inheritance that Robert has come be known as of Bellême rather than of Montgomery.
William the Conqueror died in 1087, and Robert's first act on hearing the news was to expel the ducal garrisons from his castles. Robert Curthose was the new duke of Normandy, but he was unable to keep order, and Robert of Bellême had a free hand to make war against his less powerful neighbours.

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Rebellion of 1088
The next year in the Rebellion of 1088, Odo of Bayeux rebelled in an attempt to place Curthose on the English throne in place of William Rufus. At Curthose's request Robert went to England, where he joined in the rebels' defence of Rochester Castle. The rebels were permitted to leave after the surrender of the castle and failure of the rebellion.
Robert returned to Normandy. Odo had preceded him, had obtained the confidence of the duke, and convinced Curthose that Robert was a danger to the security of the duchy. Thus Robert was arrested and imprisoned upon his disembarkation.
Robert's father Earl Roger came over from England, and, taking over his son's castles, defied Curthose. The duke captured several of the castles, but he soon tired of the matter and released Robert.
Once released, Robert returned to his wars and depredations against his neighbours in southern Normandy. He did help Curthose in putting down a revolt by the citizens of Rouen, but his motive seems to have been in large part to seize as many wealthy townspeople and their goods as possible. Curthose in turn subsequently helped Robert is some of his fights againsts his neighbours.
In 1094 one of Robert's most important castles, Domfront, was taken over by the duke's brother Henry , who never relinquished it and was to be an enemy of Robert for the rest of his life.
Later that year Robert's father earl Roger died. Robert's younger brother Hugh of Montgomery, 2nd Earl of Shrewsbury inherited the English lands and titles, while Robert inherited his father's Norman properties, which included good part of central and southern Normandy, in part adjacent to the Bellême territories he had already inherited from his mother.
In 1098 Robert's younger brother Hugh died, and Robert inherited the English properties that had been their father's, including the Rape of Arundel and the Earldom of Shrewsbury.
Robert was one of the great magnates who joined Robert Curthose's 1101 invasion of England, along with his brothers Roger the Poitevin and Arnulf of Montgomery and his nephew William of Mortain. This invasion, which aimed to depose Henry I, ended in the Treaty of Alton. The treaty called for amnesty for the participants but allowed traitors to be punished. Henry had a series of charges drawn up against Robert in 1102, and when Robert refused to answer for them, gathered his forces and besieged and captured Robert's English castles. Robert lost his English lands and titles , was banished from England, and returned to Normandy.
He was one of Curthose's commanders at the Battle of Tinchebrai and by flight from the field avoided being captured as Curthose was. With Normandy now under Henry's rule, he submitted and was allowed to retain his Norman fiefs. But after various conspiracies and plans to free Curthose, Robert was seized and imprisoned in 1112. He spent the rest of his life in prison; the exact date of his death is not known.

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Family and children
Robert married Agnes of Ponthieu, by whom he had one child, William III of Ponthieu, who via his mother inherited the county of Ponthieu.