Henry I (c. 1068 – 1 December 1135), also known as Henry Beauclerc, was King of England from 1100 to his death. Henry was the fourth son of William the Conqueror and was educated in Latin and the liberal arts. On William's death in 1087, Henry's elder brothers Robert Curthose and William Rufus inherited Normandy and England, respectively, but Henry was left landless. Henry purchased the County of Cotentin in western Normandy from Robert, but William and Robert deposed him in 1091. Henry gradually rebuilt his power base in the Cotentin and allied himself with William against Robert. Henry was present when William died in a hunting accident in 1100, and he seized the English throne, promising at his coronation to correct many of William's less popular policies. Henry married Matilda of Scotland but continued to have a large number of mistresses, by whom he had many illegitimate children.
Robert, who invaded in 1101, disputed Henry's control of England; this military campaign ended in a negotiated settlement that confirmed Henry as king. The peace was short-lived, and Henry invaded the Duchy of Normandy in 1105 and 1106, finally defeating Robert at the Battle of Tinchebray. Henry kept Robert imprisoned for the rest of his life. Henry's control of Normandy was challenged by Louis VI of France, Baldwin VII of Flanders and Fulk V of Anjou, who promoted the rival claims of Robert's son, William Clito, and supported a major rebellion in the Duchy between 1116 and 1119. Following Henry's victory at the Battle of Brémule, a favourable peace settlement was agreed with Louis in 1120.
Considered by contemporaries to be a harsh but effective ruler, Henry skilfully manipulated the barons in England and Normandy. In England, he drew on the existing Anglo-Saxon system of justice, local government and taxation, but also strengthened it with additional institutions, including the royal exchequer and itinerant justices. Normandy was also governed through a growing system of justices and an exchequer. Many of the officials who ran Henry's system were "new men" of obscure backgrounds rather than from families of high status, who rose through the ranks as administrators. Henry encouraged ecclesiastical reform, but became embroiled in a serious dispute in 1101 with Archbishop Anselm of Canterbury, which was resolved through a compromise solution in 1105. He supported the Cluniac order and played a major role in the selection of the senior clergy in England and Normandy.
Henry's only legitimate son and heir, William Adelin, drowned in the White Ship disaster of 1120, throwing the royal succession into doubt. Henry took a second wife, Adeliza, in the hope of having another son, but their marriage was childless. In response to this, Henry declared his daughter, Matilda, his heir and married her to Geoffrey of Anjou. The relationship between Henry and the couple became strained, and fighting broke out along the border with Anjou. Henry died on 1 December 1135 after a week of illness. Despite his plans for Matilda, the King was succeeded by his nephew, Stephen of Blois, resulting in a period of civil war known as the Anarchy.
The Royal style of King Henry I was "Dei Gratia Rex Anglorum" (By the Grace of God King of the English) to 1121, then "Rex Anglorum, Dux Normannorum" (King of the English, Duke of the Normans).