[6] In 1077, Robert instigated his first insurrection against his father as the result of a prank played by his younger brothers William Rufus and Henry, who had dumped a full chamber pot over his head.

Relations were not helped when King William discovered that his wife, Robert's mother Queen Matilda, was secretly sending him money.

At a battle in January 1079, Robert is said to have unhorsed King William in combat and succeeded in wounding him, only stopping his attack when he recognised his father's voice.

Of the two elder sons Robert was considered to be much weaker and was generally preferred by the nobles who held lands on both sides of the English Channel since they could more easily circumvent his authority.

In 1096, Robert formed an army and left Normandy to join the First Crusade to aid the Byzantine Empire against the Seljuk Turks and travel to Jerusalem.

[10] Crossing from Brindisi to the city of Dyrrachium in the Byzantine Empire on 5 April 1097, Robert and his army marched along the Via Egnatia and past Ohrid, Thessaloniki and the Aegean coast of Thrace on their way to Constantinople.

[12] Both then swore, as had the other crusading leaders except for Raymond of Toulouse, an oath to restore all cities that had been in Byzantine possession to Alexios and honour his superior status.

[14] At the Battle of Dorylaeum on 1 July, the crusader vanguard led by Robert and Bohemond of Taranto were ambushed and surrounded by the Seljuk Turks.

[17] Together they advanced down the Mediterranean coast and laid siege to Arqa in February but were met with failure and left on 13 May 1099 and went to Jerusalem, finally arriving outside its walls on 7 June.

[22] Instead, he travelled again to Southern Italy where he wintered again and married Sybil which also brought him a big dowry which enabled him to raise the necessary funds to buy back his duchy.

[23] When William II died on 2 August 1100, Robert was still on the return journey and absent from Normandy and would not arrive until September, allowing his other brother Henry was to seize the crown of England for himself.

Upon his return, Robert—urged by Flambard and several Anglo-Norman barons—claimed the English crown, on the basis of the short-lived agreement of 1087, and in July 1101 led an invasion to oust his brother Henry.

Robert spent the night before sporting with harlots and jesters, and while he lay in bed sleeping off his drunkenness his unworthy friends stole his clothes.

[25] In 1106, Henry defeated Robert's army decisively at the Battle of Tinchebray and claimed Normandy as a possession of the English crown, a situation that endured for almost a century.

Robert Curthose, sometime Duke of Normandy, eldest son of the Conqueror, was buried in the abbey church of St Peter in Gloucester.

William Clito was unlucky all his life; his attempts to invade Normandy failed twice (1119 and 1125), his first marriage to a daughter of the Count of Anjou was annulled by his uncle's machinations, and even his late inheritance of the county of Flanders was mishandled.

William of Malmesbury says she died as a result of binding her breasts too tightly; both Robert of Torigny and Orderic Vitalis suggest she was murdered by a cabal of noblewomen led by her husband's mistress, Agnes Giffard.