Canute II of Denmark

Canute II of Denmark, also known as Canute the Great (also spelled Cnut or Knut, c. 995– 12 November 1035), king of Denmark, England, Norway and parts of Sweden, together often referred to as the Anglo-Scandinavian or North Sea Empire. After his death, his sons fought amongst themselves, and the empire disintegrated within a decade.

As a Danish prince, Canute won the throne of England in 1016 in the wake of centuries of Viking activity in northwestern Europe. His accession to the Danish throne in 1018 brought the crowns of England and Denmark together. Canute maintained his power by uniting Danes and English under cultural bonds of wealth and custom, rather than by sheer brutality, and was remembered as a benevolent ruler. After a decade of conflict with opponents in Scandinavia, Cnut claimed the crown of Norway in Trondheim in 1028. The Swedish city Sigtuna was held by Canute, but he never controlled all of that kingdom.

A popular legend tells how King Canute, for the benefit of his foolish, flattering courtiers, had his throne placed on the beach and pretended he had the power to command the tides not to come in. When nature did not obey him, he told his audience that he was only a man and not the demigod-like figure they would have made of him. This story has often been misunderstood and inverted, to portray Canute as a deluded madman who believed he had supernatural powers.

Literary comment
Harry Turtledove occasionally has his characters use the story of Canute and the tides as a shorthand metaphor for an insurmountable task. The Two Georges, for example, has two such moments.