Cnut in the context of "Edmund Ironside"

Æthelred II c.968 – 23 April 1016), known as Æthelred the Unready, was King of the English from March 978 to December 1013 and again from February 1014 until his death in April 1016. He was the son of King Edgar (reigned 959–975) and Queen Ælfthryth. Æthelred came to the throne after the assassination of his older half-brother, King Edward the Martyr, a crime which deeply shocked people. The epithet "Unready" is a pun on his name in Old English, Æthel (noble) and ræd (counsel).

Shortly after Æthelred's accession Viking attacks resumed after a generation of peace. Minor raids in the 980s escalated to large scale attacks from the 990s, and as the English were rarely victorious in battle the king and his advisers resorted to giving the Vikings tribute to leave England, payments which are often (incorrectly) called Danegeld. In the 1000s increasingly destructive raids by Viking armies wore down English resistance, and in December 1013 King Swein Forkbeard of Denmark conquered England. Æthelred fled to Normandy, but when Swein died in February 1014 he was able to return to the throne and drive out Swein's son Cnut. In early 1015 civil war broke out when Æthelred's favourite Eadric Streona murdered close allies of Æthelred's oldest surviving son, Edmund Ironside. Cnut returned soon afterwards and Edmund and Æthelred tried to unite against him, but they were hampered by suspicion between them, Eadric's treachery and Æthelred's poor health. He died in April 1016 and Edmund carried on the war until he died in December 1016 and Cnut became king of all England.

Eadric Streona (died 1017) was Ealdorman of Mercia from 1007 until he was killed by King Cnut. Eadric was given the epithet "Streona" (translated as "The Acquisitive”) in Hemming's Cartulary because he appropriated church land and funds for himself. Eadric became infamous in the Middle Ages because of his traitorous actions during the Danish re-conquest of England.

Eadric was one of at least eight children and had relatively humble beginnings: his father Ethelric attended the court of King Æthelred the Unready, but was of no great significance and is not known to have had any titles. Even before becoming an ealdorman, Eadric seems to have acted as Æthelred's enforcer; in 1006 he instigated the killing of the Ealdorman of York, Elfhelm. Eadric was married to Æthelred's daughter Eadgyth by 1009, thus becoming his son-in-law. Eadric was appointed Ealdorman of Mercia in 1007.

Harald Sigurdsson (Old Norse: Haraldr Sigurðarson; c. 1015 – 25 September 1066), also known as Harald III of Norway and given the epithet Hardrada in the sagas, was King of Norway from 1046 to 1066. He unsuccessfully claimed the Danish throne until 1064 and the English throne in 1066. Before becoming king, Harald spent 15 years in exile as a mercenary and military commander in Kievan Rus' and chief of the Varangian Guard in the Byzantine Empire. In his chronicle, Adam of Bremen called him the "Thunderbolt of the North".

In 1030, the fifteen-year-old Harald fought in the Battle of Stiklestad alongside his half-brother Olaf Haraldsson. Olaf sought to reclaim the Norwegian throne, which he had lost to Danish king Cnut two years previously. Olaf and Harald were defeated by forces loyal to Cnut, and Harald was forced into exile to Kievan Rus'. Thereafter, he was in the army of Grand Prince Yaroslav the Wise, becoming captain, until he moved on to Constantinople with his companions around 1034. In Constantinople, he rose quickly to become the commander of the Byzantine Varangian Guard, seeing action on the Mediterranean Sea, in Asia Minor, Sicily, possibly in the Holy Land, Bulgaria and in Constantinople itself, where he became involved in the imperial dynastic disputes. Harald amassed wealth whilst in the Byzantine Empire, which he shipped to Yaroslav in Kievan Rus' for safekeeping. In 1042, he left the Byzantine Empire, returning to Kievan Rus' to prepare to reclaim the Norwegian throne. In his absence the Norwegian throne had been restored from the Danes to Olaf's illegitimate son Magnus the Good.

Æthelred II (c. 968 – 23 April 1016), known as Æthelred the Unready, was King of the English from March 978 to December 1013 and again from February 1014 until his death in April 1016. He was the son of King Edgar (reigned 959–975) and Queen Ælfthryth. Æthelred came to the throne after the assassination of his older half-brother, King Edward the Martyr (reigned 975–978), a crime which deeply shocked people. The epithet "Unready" is a pun on his name in Old English, Æthel (noble) and ræd (counsel).

Shortly after Æthelred's accession Viking attacks resumed after a generation of peace. Minor raids in the 980s escalated to large scale attacks from the 990s. As the English were rarely victorious in battle the king and his advisers resorted to giving the Vikings tribute to leave England, payments which are often (incorrectly) called Danegeld. In the 1000s increasingly destructive raids by Viking armies wore down English resistance, and in December 1013 King Swein Forkbeard of Denmark conquered England. Æthelred fled to Normandy, but when Swein died in February 1014 he was able to return to the throne and drive out Swein's son Cnut. In early 1015 civil war broke out when Æthelred's favourite Eadric Streona murdered close allies of Æthelred's oldest surviving son, Edmund Ironside. Cnut returned soon afterwards and Edmund and Æthelred tried to unite against him, but they were hampered by suspicion between them, Eadric's treachery, and Æthelred's poor health. Æthelred died in April 1016 and Edmund carried on the war until he died in December 1016 and Cnut became king of all England.

Estrid Svendsdatter of Denmark (also known as Estrith or Astrith; sometimes called Margaret; fl. 1017–1032; c. 990s – after 1057 and before 1073) was a prominent Danish princess and titular queen of the Jelling dynasty, half-sister of Cnut the Great and wife of the magnate Ulf Jarl. She was the mother of Sweyn II Estridsen, during whose reign she was commonly styled dronning (“queen”) in Denmark, though she was never queen regnant nor a king's consort. Through Estrid, Sweyn traced his claim to the Danish throne and founded the matronymic House of Estridsen, which ruled from 1047 to 1412.

Medieval sources diverge on several points of her life. She was a daughter of Sweyn Forkbeard, but her mother is variously identified in sources as Sigrid the Haughty or, in earlier scholarship, as the Slavic princess sometimes called Gunhild of Wenden, a view now generally rejected. After Sweyn's death in 1014, Estrid came under Cnut's guardianship. He married her to a son of Grand Prince Vladimir the Great or Yaroslav the Wise, but the prince died shortly afterwards. Several western chroniclers, including Rodulfus Glaber and Adam of Bremen, record a proposed or short-lived marriage with the duke of Normandy (probably Robert I, Duke of Normandy), though the precise details remain uncertain. By the early 1020s, she was married to the English magnate Ulf Thorgilsson, who later served as regent in Denmark. By marriage she was thus, successively, a Russian princess, duchess of Normandy and a Danish noblewoman.

Edward the Exile (c. 1016 – 19 April 1057), also called Edward Ætheling, was the son of King Edmund Ironside and of Ealdgyth. He spent most of his life in exile in the Kingdom of Hungary following the defeat of his father by Cnut.

Earl of Northumbria or Ealdorman of Northumbria was a title in the late Anglo-Saxon, Anglo-Scandinavian and early Anglo-Norman period in England. The ealdordom was a successor of the Norse Kingdom of York. In the seventh century, the Anglo-Saxon kingdoms of Bernicia and Deira were united in the kingdom of Northumbria, but this was destroyed by the Vikings in 867. Southern Northumbria, the former Deira, then became the Viking kingdom of York, while the rulers of Bamburgh commanded territory roughly equivalent to the northern kingdom of Bernicia. In 1006 Uhtred the Bold, ruler of Bamburgh, by command of Æthelred the Unready became ealdorman in the south, temporarily re-uniting much of the area of Northumbria into a single jurisdiction. Uhtred was murdered in 1016, and Cnut then appointed Eric of Hlathir ealdorman at York, but Uhtred's dynasty held onto Bamburgh. After the Norman Conquest the region was divided into multiple smaller baronies, one of which was the earldom of Northumberland, with others like the earldoms of York and numerous autonomous liberties such as the County Palatine of Durham and Liberty of Tynedale.