The final battle in the movie, Brunanburh, was fought on the Wirral. However, the issue with this is that we do not know where the battle occurred. The contemporary Anglo-Saxon Chronicle recorded a battle 'by Brunanburh' without explaining where 'Brunanburh' was located. The first person who provided information on the battle's location was John of Worcester in Chronicon ex chronicis, completed in the 1120s. According to John, the invaders ‘entered the mouth of the [River] Humber with a powerful fleet'. This has led some historians, including Michael Wood (University of Manchester), to suggest that the most likely location for the battle was in Southern Yorkshire. Wood's version of events is that Anlaf sailed up the River Humber, seized the town of York, named himself King and gained the support of the locals, then marched south with his Celtic allies and met Æthelstan in battle between the borders of Mercia and York. Yet, one should be wary of solely relying on John of Worcester for the battle's location, as he was writing almost 200 years after the battle. This time gap between the battle and John's chronicle leads us to ask where he obtained his information regarding the river Humber. Some historians have argued that he made it up, as there are no prior records which make any suggestion of the Humber route. This has been countered by Wood, who believes John had access to a northern chronicle composed at York, now lost to us. Those who doubt John's account claim he assumed an invasion via the River Humber was the most likely route of a Viking invasion, as he was influenced by the accounts of the invasions of Harald Hardrada in 1066 and King Sweyn II of Denmark in 1069, both of whom entered England via the Humber. Thus, John assumed the invasion of 937 followed the same route.
The alternative location to South Yorkshire is the Wirral. This was first suggested by Albert Hugh Smith in 1937. The argument for the Wirral location is based on the name of the town of Bromborough, Merseyside, being derived from the Old English name 'Brunanburh'. The Wirral was also an area of Scandinavian settlement and was thought to have a harbour on its northern coast. Thus, it was a friendly and accessible landing site for a Viking invasion and was only a short distance for the Dublin fleet to travel. The main criticism of the Wirral location, however, is that there is no hard evidence for it. It is based on assumptions and what would have been pragmatic for the military leaders involved. The Bromborough-Brunanburh name connection is also not accepted by all scholars.
Part of the dispute between the Yorkshire and Wirral locations is regarding the nature of the Brunanburh campaign. For Wood and the Yorkshire advocates, the war was part of the broader conflict between the House of Wessex and the Uí Ímair for control of York and, by extension, northern England, which lasted from 927 (Æthelstan's conquest of York) to 952 (the ousting of the last Uí Ímair king of York). During this war, when the Uí Ímair later reclaimed York, many battles and diplomatic agreements took place in Yorkshire. The Roman Road going from York-Castleford-Derby was also often used by both sides to march north and south into enemy territory, making the York-Mercia border region (South Yorkshire) near the York-Castleford-Derby route a possible zone of conflict. If Anlaf's objective was York, it was indeed easiest for him to sail around Northern Britain to York via the river Humber. At York, he could proclaim himself king, take oaths of loyalty from the local lords, and then, with their support, march south to face the English rather than landing in the Wirral, from where an English army would have stood between him and York.
However, for Michael Livingston (Military College of South Carolina), who advocates for the Wirral location, this war was not merely part of the ongoing conflict between the House of Wessex and the Uí Ímair over York. Instead, it was a unique one-off attempt by the northern Celtic kings, in alliance with several Viking warlords, to crush the power of Æthelstan. Taking York was undoubtedly part of this plan but was not the central focus and was of less interest to the Celts. Livingston points out the uniqueness of Brunanburh, which makes it distinct from the broader conflict between the House of Wessex and the Uí Ímair, particularly the size of the invading fleet, claimed to be 615 ships and the involvement of Scotland and Strathclyde. These northern Celtic kingdoms barely played any role in the conflicts between the House of Wessex and the Uí Ímair before and after Brunanburh. As Christian kingdoms, who had both suffered at the hands of Viking attacks, they were not natural Viking allies. King Constantine II of Scotland’s predecessor had died at the hands of Viking raiders. Constantine himself fought the Uí Ímair in 904, killing Anlaf’s cousin and faced Anlaf’s uncle in 918 at the Battle of Corbridge. Yet now, Constantine had been humiliated by Æthelstan, who, in addition to making Constantine a sub-king, had invaded Scotland in 934. Constantine was likely willing to forget the past in order to harm Æthelstan, who was now a greater threat to Scotland than the Uí Ímair. According to Livingston, the goal of Anlaf and his allies was not merely York; it was the whole of the Viking lands (the Danelaw), which had been occupied in the 870s before the West Saxon resurgence in the 910s-920s.
The ideal location for this broad coalition to rendezvous would be the Wirral, being close to both Anlaf in Dublin and the King of Strathclyde and as close to the Scots as York was. For Anlaf in particular, the voyage to the Wirral was only about 125 miles, compared to the 930-mile journey to York, which would have allowed more opportunities for his fleet to go hungry, be shipwrecked, be lost or mutiny. There were also several other strategic advantages to landing the invading fleet on the Wirral. It was also near enough for kings in Northern Wales to join with the fleet if they wished to oppose Æthelstan, something that Anlaf and his allies may have hoped for before the battle. This region of Mercia, near Chester, had also previously demonstrated hostility toward the House of Wessex, rebelling against Æthelstan's father in 924 and thus may have been unwilling to oppose the invaders. Livingston further points out that if the River Humber and the town of York were used by the invaders, it would be strange for early scribes not to mention this, as both are well-known landmarks in England. Instead, the lack of mention of any definitive location would suggest that the battle was fought in an obscure and not well-known location. The Wirral fits this, as it was away from the centres of power in Winchester and York and had long been a contested border region between Mercia and Northumbria.
Unfortunately, the site of the battle may never be discovered. Yet, there is no sign on either the Wirral or Yorkshire sides of the argument of giving up. Seven Kings Must Die will likely give this mystery more attention and interest from the public. Indeed, both sides are sharpening their blades. Michael Wood is still preparing his much anticipated and long-awaited biography of King Æthelstan, which will undoubtedly reassert the Yorkshire argument. While local archaeologists in the Wirral, having set up 'The search for the Battle of Brunanburh' project, grow more confident in the Wirral location with each Viking artefact they find. The movie provides us with a heart-warming and conclusive ending, where Uhtred makes his peace with Æthelstan, finally forming a united Kingdom of England. We are not told if Uhtred lives after the movie, yet his work was done, and the mission that Alfred the Great dreamt of at the start of the series was fulfilled. However, historically, this was not the end of the story. Æthelstan would only live two more years, dying in 939, opening up the north to Anlaf's return and a continued war over control of York, unleashing chaos in northern England for the next two decades. Seven different kings would rule York in the 15 years that followed Æthelstan’s death. The town was only fully restored to West Saxon control in 954, with the death of the last king of York, Erik Bloodaxe.