The Fortress Kingdom: The Wars of Aethelflaed and Edward the Elder, 899–927

Review

by Michael McComb
published on 23 July 2025

Paul Hill provides a detailed and well-researched reminder that England was not merely imagined into existence or won by a single epoch-defining battle. It was forged over several decades through the unglamorous and grim business of fortress building, slow methodical advances, and military cooperation between two very capable siblings.

When Alfred the Great – often presented as England’s founding father – died in 899, much of England was still under Viking rule. His kingdom was restricted to the southern realms of Wessex (south of the Thames) and western Mercia (West Midlands). Yet, by 927, his grandson, Aethelstan (reign 924-939), would claim sovereignty over all England. What happened in the intervening three decades to allow for such an expansion of power? This is the question Paul Hill tackles in The Fortress Kingdom: The Wars of Aethelflaed & Edward the Elder, 899-927.

Hill, formerly curator of Kingston-upon-Thames Museum, is the author of ten books on medieval warfare, including The Road to Hastings (2005) and The Wars of Alfred the Great (2022). His focus in this latest work is now on the achievements of Alfred’s children: his formidable daughter, Aethelflaed (870-918), and his all-conquering son, Edward the Elder (874-924).

Divided into five parts, The Fortress Kingdom begins with Alfred’s death in 899 and the emergence of Edward’s rule in Wessex and Aethelflaed’s in Mercia. It follows the siblings through their successful defensive and then offensive campaigns against the Vikings, to Edward’s takeover of Mercia in 918, following Aethelflaed’s death, and finally ending with the early reign of Edward’s son, Aethelstan, and his conquest of northern England in 927.

The book’s title, The Fortress Kingdom, alludes to the military strategy at the heart of this conflict. Fortresses (or burhs), guarded by wooden ramparts and deep ditches, were primarily an innovation of Alfred’s and were used to defend his kingdom from the Vikings. However, under his successors, they became instruments of aggression and conquest. Used as springboards for invasions into Viking territory, successful campaigns would be followed up by fortifying captured Viking settlements or building new fortresses at strategic locations, consolidating control over conquered lands.

Chapter Six, “How did a Fortress Work," is particularly useful in explaining this process. Here, readers learn about the machinery behind these fortresses – the numbers in a garrison, the road networks linking them, and the beacon system, which gave each fortress early warning of incoming attacks.

Some may find the search for vanished fortresses disruptive to the book's narrative – was Scergate in Shropshire or Gloucestershire? However, such details are essential in a book so deeply rooted in military geography. With this in mind, Hill makes good use of his 24 in-text "Maps and Plans," showing each fortress’s location, their proximity to one another, and how they might have looked.

The main challenge for the historian of this period is to expand upon the often dry and limited primary sources, which typically merely state that Edward or Aethelflaed captured a certain fortress in a certain year. Yet, in Hill’s account of these fortress battles, he explores broader considerations, including strategic cooperation between the siblings, diplomacy with Celtic kings, negotiations with defeated Viking leaders, and explains how these fortresses became centres of commerce, faith, and urban life.

With its focus primarily on warfare and fortified towns, The Fortress Kingdom is not an extensive dual biography of Aethelflaed and Edward. For readers seeking more detailed personal portraits, Tim Clarkson’s Aethelflaed: Lady of the Mercians (2018) and Michael John Key’s Edward the Elder: King of the Anglo-Saxons (2019) are worthy alternatives. However, this book is unique as it focuses solely on the siblings collectively as military leaders and partners.

While the book targets a general audience and is an engaging and accessible read, its scope is limited to the 28 years from 899 to 927. Thus, newcomers to the Anglo-Saxon period might prefer to start with broader works, such as Marc Morris’s The Anglo-Saxons: A History of the Beginnings of England (2021), or first read Hill’s earlier book on Alfred, before moving on to his latest work. However, those already familiar with early English history will find The Fortress Kingdom an excellent contribution to the existing literature on tenth-century England.

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