Harthacnut was the son of King Cnut the Great (who ruled Denmark, Norway, and England) and Emma of Normandy.

[3] In the 1020s, Denmark was threatened by Norway and Sweden, and in 1026 Cnut decided to strengthen its defences by bringing over his eight-year-old son to be the future king under a council headed by his brother-in-law, Earl Ulf.

Harthacnut was a close ally of Svein, but he did not feel his resources were great enough to launch an invasion of Norway, and the half-brothers looked for help from their father, but instead they received news of his death in November 1035.

[1] He was unable to come to England in view of the situation in Denmark, and it was agreed that Svein's full brother, Harold Harefoot, should act as regent, with Emma holding Wessex on Harthacnut's behalf.

In 1037, Harold was generally accepted as king, Harthacnut being, in the words of the Anglo-Saxon Chronicle, "forsaken because he was too long in Denmark",[6] while Emma fled to Bruges, in Flanders.

In 1039, Harthacnut sailed with ten ships to meet his mother in Bruges but delayed an invasion as it was clear Harold was sick and would soon die, which he did in March 1040.

While the general outline of events following Cnut's death is clear, the details are obscure, and historians give differing interpretations.

The historian M. K. Lawson states that it is unclear whether Harthacnut was to have England as well as Denmark, but it was probably a reflection of a formal arrangement that mints south of the Thames produced silver pennies in his name, while those to the north were almost all Harold's.

He probably stayed in Denmark because of the threat from Magnus of Norway, but they eventually made a treaty by which if either died without an heir, his kingdom would go to the other, and this may have freed Harthacnut to pursue his claim to England.

[12] The crews had to be rewarded for their service, and to pay them, he levied a geld of more than 21,000 pounds, a huge sum of money that made him unpopular, although it was only a quarter of the amount his father had raised in similar circumstances in 1017–1018.

[14] Godwin, the powerful earl of Wessex, had been complicit in the crime as he had handed over Alfred to Harold, and Queen Emma charged him in a trial before Harthacnut and members of his council.

[15] Bishop Lyfing of Worcester was also charged with complicity in the crime and deprived of his see, but in 1041 he made his peace with Harthacnut and was restored to his position.

He doubled the size of the English fleet from sixteen to thirty-two ships, partly so that he had a force capable of dealing with trouble elsewhere in his empire,[16] and to pay for it he severely increased the rate of taxation.

[2][17] Although the city was burnt and plundered, citizens of Worcester who had taken refuge on an island in the River Severn fought successfully against Harthacnut's troops, and won the right to return to their homes without further punishment.

Very few contemporary documents survive, but a royal charter of his transferred land to Bishop Ælfwine of Winchester, and he made several grants to Ramsey Abbey.

Lawson comments: "This may mean that Edward was recognized as heir of Harthacnut, who had neither wife nor children, and who is said by the slightly later Norman historian William of Poitiers to have suffered from frequent illness.

The likely truth of this is suggested not only by his sudden death the following year, but also because it is otherwise difficult to see why a man in his early twenties with a normal life expectancy should have acted so."

[24] According to the Anglo-Saxon Chronicle, "Harthacnut died as he stood at his drink, and he suddenly fell to the earth with an awful convulsion; and those who were close by took hold of him, and he spoke no word afterwards".

The Heimskringla depicts Edward portraying himself as brother and legal heir to both Harold Harefoot and Harthacnut, while pointing out that he had already won the support "of all the people of the country".

Whether Magnus defeated him in war or not, he was told: "You can never be called king in England, and you will never be granted any allegiance there before you put an end to my life."

From Henry's perspective, it was probably orchestrated to allow the Holy Roman Empire to claim control of Denmark and the western areas of the Baltic Sea.

In the view of M. K. Lawson, he had at least two of the requisites of a successful medieval king: he was "both ruthless and feared"; had he not died young, the Norman Conquest might not have happened.

[31] Henry of Huntingdon (12th century) claimed that Harthacnut ordered for the dining tables of his court to be "laid four times a day with royal sumptuousness" which O'Brien says is likely a popular myth.

He portrays Harold as lacking in chivalry, courtesy or honour, and Harthacnut as "a noble knight and stalwart of body, and he greatly loved knighthood and all virtues".

He praises Harthacnut for his generosity with food and drink, writing that his table was open "for all who wished to come to his court to be richly served with royal dishes".