While Brunsden provides a solid attempt at recounting the life of Thorfinn Sigurdarson, the eleventh-century earl of Orkney, his study lacks nuance in its dealings with its sources and the presentation of its arguments. Thorfinn the Mighty has its place as a popular history of Orkney at the end of the Viking Age and of the life of Thorfinn, and makes its subject approachable to the average lay reader who either lacks any prior knowledge of, or has only a passing interest in, the period or figures in question. Mainly drawing on literary sources, most heavily on Orkneyinga saga, Brunsden paints a vivid picture of the earl Thorfinn, but does not contextualize his sources. Instead, the author either takes the texts too literally, or else strongly questions them. Brunsden relies on Orkneyinga saga for specific facts about the lives of Thorfinn and those with whom he interacts, and on eddic poetry to give a general sense of the historical period and “Viking” values and beliefs. These types of sources are often only vaguely identified as Icelandic or saga “tradition” (e.g. 18, 35, 70, 95), and the lack of subtlety with which the sources are understood by the author becomes at times aggravating for anyone with the understanding that medieval Icelandic literature is in fact literature, and should no longer be mined for historical information without great caution.

Brunsden’s great attachment to the idea of Thorfinn as “ultimate Viking” is also cause for concern, as the notion of what constitutes a Viking is never really defined at any point in the text, but is rather assumed knowledge, perhaps thought too obvious for definition. The closest the author comes to indicating what he means by the term Viking is to quote eddic poetry as an authority on the worldview of the Viking Age throughout the work, again without commenting on how we have come to know these poems today. For example, speaking of Orkney earls, including Thorfinn, Brunsden quotes Hávamál 76: “the most illustrious lived (and died) by the maxim: Cattle die, kinsmen die …” (26); additionally, after noting Thorfinn’s death in 1065, Brunsden says that “even the uncommonly accomplished are slaves to their urður (fate, doom), and must one day face the ultimate inevitability: ‘The foolish man thinks he will live forever / if he keeps away from fighting’” (124), quoting Hávamál 16. That a historical figure could be lauded as the “ultimate Viking” is simply taken for granted, and the author has no desire to interrogate this notion further.

In the first two chapters, the book addresses Orkney as a location in relation to the Norwegian and Scottish powers surrounding it, the culture that thrived during the Viking Age, and earl Thorfinn’s ancestors’ and father’s place there. Thorfinn’s early years, when he ruled only a part of the Orkney earldom, are also described, up until the early 1030s when Thorfinn came to rule the whole of Orkney. The third and fourth chapters look at the first part of Thorfinn’s rule as earl of Orkney and his various accomplishments and conflicts with other Scottish rulers, including a large portion devoted to Macbeth Macfinlay, known from Orkneyinga saga only as Karl Hundason. Brunsden is quick to identify these two figures as one and the same person. Despite the lack of any solid evidence to confirm that Karl Hundason is in fact Macbeth, and despite Chapter Three being titled “The Ultimate Viking at War with Karl Hundason,” he consistently refers to Thorfinn’s opponent as Macbeth, in one of many examples in which the author puts too much trust in a single source for a specific purpose, without questioning it. The account of Thorfinn’s partnership with his nephew Rognavald Brusason in Chapter Four, including their raids on the neighbouring areas of Scotland, England, the Isle of Man, and Ireland to increase the size of the earldom, plays out similarly, with the author alternately skeptical or critical of Orkneyinga saga (e.g. 77), and embracing its words (e.g. 74), when it suits him. The overall impression is that the author treats this text as a contemporary source for the events it describes, without seeming to understand fully the great remove it is from those events of around two hundred years earlier, and so he sometimes has expectations unsuitable for a literary text—even one that might aim to recount history.

The fifth and sixth chapters detail Thorfinn’s later ruling years and death. Chapter Five includes a lengthy section discussing Thorfinn’s marriage to Ingibjorg Finnsdottir, attempting to discern the bride’s age at betrothal and marriage, about which there appears to be some confusion, requiring Brunsden to speculate on matters that seem overly complex for a historical work of this kind (esp. 86–87). Thorfinn’s disputes with Rognavald, ending in the latter’s death, and thus Thorfinn’s regaining of the entire Orkney earldom are also detailed, and at times narrated—without comment—as if based on eyewitness reports (97–100). As indicated in its title, Chapter Six discusses Thorfinn’s shift from “Ultimate Viking” to “Ultimate Prince,” which is how Brunsden describes him once he turns from fighting and claiming more territory to focusing on administering what territory he does have and establishing Christianity in Orkney. The chapter includes a discussion of Thorfinn’s pilgrimage to Rome (via Norway, Denmark, and Germany), which ends with a quite unnecessarily speculative and unamusing mention of his “audience with the pope, who would absolve the earl of (what might have been) a near record level of lifetime sins” (110); unfortunately this type of meaningless speculation and failed attempt at humour appears throughout much of the book. The brief seventh and final chapter looks back on Thorfinn’s life and forward to the history of Orkney and his earldom after his death, including his children’s inability to maintain the earldom they inherited, which quickly disintegrated in the later years of the eleventh century.

Overall, Thorfinn the Mighty: The Ultimate Viking succeeds in recounting the life of Thorfinn, the earl of Orkney in the eleventh century, but while it excels as a popular history aimed at the lay reader with an interest in Orkney or “Viking” history, it falls short as an academic work. It almost seems that the less the reader of this book knows about Orkney or Scandinavian history, or about Old Norse-Icelandic literature, the better it might be enjoyed.