At the Battle of Nesjar, in 1016, Olaf Haraldsson won the kingdom of Norway from the Danes.
It was at some time after Erikr left for England, and on the death of Svein while retreating to Sweden, maybe intent on returning to Norway with reinforcements, that Erikr's son Hakon went to join his father and support Cnut in England, too.

Cnut's brother Harald may have been at Cnut's coronation, in 1016, returning to Denmark as its king, with part of the fleet, at some point thereafter.
It is only certain, though, that there was an entry of his name, alongside Cnut's, in confraternity with Christ Church, Canterbury, in 1018.
This is not conclusive, though, for the entry may have been made in Harald's absence, perhaps by the hand of Cnut himself, which means that, while it is usually thought that Harald died in 1018, it is unsure whether he was still alive at this point.
Entry of his brother's name in the Canterbury codex may have been Cnut's attempt to make his vengeance for Harald's murder good with the Church.
This may have been just a gesture for a soul to be under the protection of God.
There is evidence Cnut was in battle with pirates in 1018, with his destruction of the crews of thirty ships, although it is unknown if this was off the English or Danish shores.
He himself mentions troubles in his 1019 letter (to England, from Denmark), written as the King of England and Denmark.
These events can be seen, with plausibility, to be in connection with the death of Harald.
Cnut says he dealt with dissenters to ensure Denmark was free to assist England:
King Cnut greets in friendship his archbishop and his diocesan bishops and Earl Thurkil and all his earls ... ecclesiastic and lay, in England ... I inform you that I will be a gracious lord and a faithfull observer of God's rights and just secular law. (
He exhorts his ealdormen to assist the bishops in the maintenance of) God's rights ... and the benefit of the people.

If anyone, ecclesiastic or layman, Dane or Englishman, is so presumptuous as to defy God's law and my royal authority or the secular laws, and he will not make amends and desist according to the direction of my bishops, I then pray, and also command, Earl Thurkil, if he can, to cause the evil-doer to do right.
And if he cannot, then it is my will that with the power of us both he shall destroy him in the land or drive him out of the land, whether he be of high or low rank.
And it is my will that all the nation, ecclesiastical and lay, shall steadfastly observe Edgar's laws, which all men have chosen and sworn at Oxford.


Since I did not spare my money, as long as hostility was threatening you, I with God's help have put an end to it.
Then I was informed that greater danger was approaching us than we liked at all; and then I went myself with the men who accompanied me to Denmark, from where the greatest injury had come to us, and with God's help I have made it so that never henceforth shall hostility reach you from there as long as you support me rightly and my life lasts.
Now I thank Almighty God for his help and his mercy, that I have settled the great dangers which were approaching us that we need fear no danger to us from there; but we may rekon on full help and deliverance, if we need it.

— Cnut's letter of 1019, Trow 2005, pp.
 168–169
At the Battle of Nesjar, in 1016, Olaf Haraldsson won the kingdom of Norway from the Danes. It was at some time after Erikr left for England, and on the death of Svein while retreating to Sweden, maybe intent on returning to Norway with reinforcements, that Erikr's son Hakon went to join his father and support Cnut in England, too.
Cnut's brother Harald may have been at Cnut's coronation, in 1016, returning to Denmark as its king, with part of the fleet, at some point thereafter. It is only certain, though, that there was an entry of his name, alongside Cnut's, in confraternity with Christ Church, Canterbury, in 1018. This is not conclusive, though, for the entry may have been made in Harald's absence, perhaps by the hand of Cnut himself, which means that, while it is usually thought that Harald died in 1018, it is unsure whether he was still alive at this point. Entry of his brother's name in the Canterbury codex may have been Cnut's attempt to make his vengeance for Harald's murder good with the Church. This may have been just a gesture for a soul to be under the protection of God. There is evidence Cnut was in battle with pirates in 1018, with his destruction of the crews of thirty ships, although it is unknown if this was off the English or Danish shores. He himself mentions troubles in his 1019 letter (to England, from Denmark), written as the King of England and Denmark. These events can be seen, with plausibility, to be in connection with the death of Harald. Cnut says he dealt with dissenters to ensure Denmark was free to assist England:
King Cnut greets in friendship his archbishop and his diocesan bishops and Earl Thurkil and all his earls ... ecclesiastic and lay, in England ... I inform you that I will be a gracious lord and a faithfull observer of God's rights and just secular law. (He exhorts his ealdormen to assist the bishops in the maintenance of) God's rights ... and the benefit of the people.
If anyone, ecclesiastic or layman, Dane or Englishman, is so presumptuous as to defy God's law and my royal authority or the secular laws, and he will not make amends and desist according to the direction of my bishops, I then pray, and also command, Earl Thurkil, if he can, to cause the evil-doer to do right. And if he cannot, then it is my will that with the power of us both he shall destroy him in the land or drive him out of the land, whether he be of high or low rank. And it is my will that all the nation, ecclesiastical and lay, shall steadfastly observe Edgar's laws, which all men have chosen and sworn at Oxford.

Since I did not spare my money, as long as hostility was threatening you, I with God's help have put an end to it. Then I was informed that greater danger was approaching us than we liked at all; and then I went myself with the men who accompanied me to Denmark, from where the greatest injury had come to us, and with God's help I have made it so that never henceforth shall hostility reach you from there as long as you support me rightly and my life lasts. Now I thank Almighty God for his help and his mercy, that I have settled the great dangers which were approaching us that we need fear no danger to us from there; but we may rekon on full help and deliverance, if we need it.
— Cnut's letter of 1019, Trow 2005, pp. 168–169
Cnut the Great