[3][4][5][6] Canute was the only legitimate son of King Eric I of Denmark (died 1103) and Boedil Thurgotsdatter, but as a minor he was bypassed in the election of 1104.

In 1115, his uncle, King Niels of Denmark, placed him in charge of the Duchy of Schleswig (jarl af Sønderjylland) in order to put an end to the attacks of the Slavic Obotrites.

During the next fifteen years, he fulfilled his duty of establishing peace in the border area so well that he was titled Duke of Holstein (Hertug af Holsten) and became a vassal of the Holy Roman Empire.

[7] He seems to have been the first member of the Danish royal family who was attracted by the knightly ideals and habits of medieval Germany, indicated by his changing his title to Duke of Schleswig (Hertug af Slesvig).

the death provoked a civil war that continued intermittently until 1157, ending only with the triumph of Canute's posthumous son Valdemar I.