Henry I (c. 1068/1069 - 1 December 1135) was the fourth son of William I the Conqueror, the first King of England after the Norman Conquest of 1066. He succeeded his elder brother William II as King of England in 1100 and defeated his eldest brother, Robert Curthose, to become Duke of Normandy in 1106. He was called Beauclerc for his scholarly interests and Lion of Justice for refinements which he brought about in the rudimentary administrative and legislative machinery of the time. Henry's reign is noted for its political opportunism. His succession was confirmed while his brother Robert was away on the First Crusade and the beginning of his reign was occupied by wars with Robert for control of England and Normandy. He successfully reunited the two realms again after their separation on his father's death in 1087. Upon his succession he granted the baronage a Charter of Liberties, which formed a basis for subsequent challenges to rights of kings and presaged Magna Carta, which subjected the King to law.