Cnut: The North Sea King

by Michael McComb
published on 18 February 2026

"Cnut: The North Sea King" by Ryan Lavelle is a short and engaging biography of the most ambitious and successful Scandinavian leader of the Viking Age. Lavelle captures both the brutality and pragmatism that allowed Cnut to govern England effectively for almost two decades, despite being an outsider and a foreign conqueror.

In 1066 and All That (1930), a parody book of English history, Cnut is described as a "bad king," who "became a good king." While this is a simplistic overview, it captures the essence of the portrait Ryan Lavelle paints in Cnut: The North Sea King (2017).

Lavelle is a Professor of History at the University of Winchester and the author of Aethelred II: King of the English, 978-1016 (2002) and Alfred's Wars (2010). Across six chapters, he begins with Cnut's conquest of England in 1016, then covers the brutality of his early regime and succession to the Danish throne in 1018. Chapter Four shifts to his conquest of Norway in 1028 and his relations with Normandy and Germany, while Chapter Five explains Cnut's approach to the church. Finally, the book concludes with Cnut's death in 1035 and the fall of his empire shortly after.

Arriving from his Danish homeland in 1015, still in his late teens, Cnut's initial attempt at conquest in England was only partly successful. His long campaign against the English warrior king, Edmund Ironside (r. 1016), ended in a stalemate and a treaty to divide England, until Edmund died a few months later, and the whole kingdom fell to Cnut.

While Lavelle considers it unlikely that Cnut was involved in Edmund's death, his early rule was violent and bloody. Several of England's leading ealdormen were murdered, along with Edmund's brother, Eadwig. In Cnut's darkest moment, even Edmund's infant sons were sent to Scandinavia to be murdered – fortunately, they were spared by their appointed executors. Although a modern audience might wince at such brutality, Lavelle explains that such political violence was "[not] unusual in eleventh-century Europe," and that Edmund's father, Aethelred the Unready (r. 978-1016), was equally ruthless with his own magnates.

Cnut's early violence had its intended effect, and the rest of his rule in England was remarkably peaceful and stable. This was also, however, because Cnut recognised that he needed to present himself as a legitimate English king. In pursuit of this, Lavelle outlines how he adopted the identity of "a fully fledged member of the West Saxon royal kin." Cnut's transition into a pious son of Wessex included portraying himself and Edmund Ironside as "fellows and sworn brothers" in the written records of their conflict, marrying Emma of Normandy (Aethelred's widow), and reaffirming the laws of Edgar the Peaceful (Aethelred's father). He also patronised and promoted the cults of St Edward the Martyr and St Edith of Wilton (Aethelred's brother and sister). Far from the foreign conqueror he was, Cnut cast himself as the rightful heir to the dynasty he had destroyed.

Lavelle, however, also notes the limits of Cnut's success and the crisis of his later years. Illness and fear of a Norman invasion (to restore their royal West Saxon relatives) meant Cnut was confined to southern England in the final years of his life. Meanwhile, from 1034, Norway was in revolt, deposing Cnut's unpopular regent and first wife, Aelfgifu. For Lavelle, this went to the heart of Cnut's difficulty in managing his empire, as it was entirely built on his own "force of personality," making it almost inevitable that it would die with him, or at least when he could no longer personally assert himself over his territories.

It might have helped the final chapter if Lavelle speculated more about Cnut's succession plan – did he intend to divide his empire between his sons (as indeed happened), or keep it intact for another generation? However, sources from the period on this matter are so conflicting and biased that it remains an admittedly challenging task.

Overall, in just under 90 pages, Lavelle offers a concise yet informative introduction to England's most capable ruler between the reigns of Aethelstan (r. 924-939) and William the Conqueror (r. 1066-1087), which is easily accessible for newcomers to the period.

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