Upon Sweyn Forkbeard's death, Canute's brother Harald was King of Denmark. Canute went to Harald to ask for his assistance in the conquest of England, and the division of the Danish kingdom. His plea for division of kingship was denied, though, and the Danish kingdom remained wholly in the hands of his brother, although, Harald lent to Canute the command of the Danes in any attempt he had a mind to make on the English throne. Harald probably saw it was out of his hands anyway. It was a vendetta that held his brother, Canute, and the Vikings driven away in spite of their conquest with Forkbeard. They were bound to fight again, on the basis of vengeance for betrayal.
It is possible Harald was at the siege of London, and the King of Denmark was content with Canute in control of the army. His name was to enter the fraternity of Christ Church, Canterbury, at some point, in 1018, although it is unsure if it was before or after he went home to Denmark with the invasion fleet of his Danes.
In 1018, Harold II died and Canute succeeded him. In 1019, he was to return to Denmark to over-winter, and affirm his succession to the Danish crown. With a Letter in which he states intentions to avert troubles to be done against England, it seems Danes were set against him, and the attack on the Wends was possibly part of his suppression of dissent. In the spring of 1020 he was back in England, his hold on Denmark presumably stable. Ulf Jarl, his brother-in-law, was his appointee as the Earl of Denmark.