Who was Aethelred Lord of Mercia and what did he do?

Not to be confused with seventh century Mercian king Æthelred I or the famous Anglo-Saxon ruler Æthelred the Unready, the history of Æthelred, Lord of the Mercians is less well known. The life of this incredible ruler straddles the last years of the heptarchy and the beginning of Anglo-Saxon England. Read on to discover who he was.

History Rulers
24 April 2023

Æthelred of Mercia was a pivotal figure of his time. This enigmatic Lord of Mercia played a crucial role in the unification of Anglo-Saxon England during the tumultuous 9th century.

Britain in the ninth century was going through a seismic change. The heptarchy – seven kingdoms that emerged after the Romans left in the fifth century – was reduced to four by around 800, these being Northumbria, Wessex, Mercia and East Anglia. By the end of the century, only Wessex was left as a truly independent kingdom.

During Viking incursions, Alfred the Great – the powerful king of Wessex – and Aethelred of Mercia formed a political and familial partnership that took the first steps in a process which would eventually lead to the unification of England.

Here is the story of Aethelred, Lord of the Mercians.

The Early Life of Aethelred

Alfred The Great (Photo: Print Collector via Getty Images)

Almost nothing is known about the early life of Aethelred of Mercia. Some sources suggest he may have been the son of Burgred, who was king of Mercia from 852 until 874, though there’s little concrete evidence that he was related to the kings of Mercia.

In the 860s and 870s, the situation in Mercia was critical, as increasing pressure from the Vikings was brought to bear. The Vikings turned their full force against Mercia in 874. They forced King Burgred into exile and installed a puppet ruler, Ceolwulf II, in his place.

Viking incursions continued to destabilise Mercia, with its territories gradually shrinking under the relentless pressure. Amid this turmoil, Æthelred emerged as a Mercian leader, eventually accepting the lordship of Alfred the Great of Wessex.

This alliance between Mercia and Wessex marked a turning point in the struggle against the Viking invaders, as the two kingdoms united their efforts to protect and eventually reclaim their lands.

Aethelred, Mercian Ruler in Name Only

Historical map of England (Photo: HodagMedia via Getty Images)

The exact circumstances of how Æthelred became the leader of Mercia are not well documented, though it’s clear he emerged as a Mercian leader during the period of political turmoil and fragmentation caused by Viking invasions.

Like much of the life of Aethelred, there is much debate over how much power he wielded. It is generally agreed that for major decisions, approval was required from Alfred.

What’s also clear is that almost nowhere is Aethelred referred to as king of Mercia. Most often he’s known as Æthelred, Lord of the Mercians or Ealdorman Aethelred of Mercia. In a number of charters he was referred to as dux et patricius (leader and nobleman) or even as procurator. This, as well as the belief that no coins were struck in his name, suggests that he probably assumed the position of a sub-ruler.

Over the next several years, Æthelred and Alfred engaged in numerous battles against the Vikings, gradually pushing them back and restoring some semblance of stability to Mercia.

On their western front, Aethelred may even have been the leader of a Mercian army – known by the epithet Edryd Long-Hair – who invaded Gwynedd and was defeated in 881 at the Battle of the Conwy. This defeat effectively led to the end of Mercia’s rule of north Wales.

This defeat, along with the constant Viking attacks, made Mercia increasingly dependent on support from Wessex. By 883, with Mercian power fading, what was once the most powerful kingdom in the land effectively became a sub-kingdom of Wessex, under the overlordship of Alfred the Great.

Yet this was a dramatic turning point in English history. For the first time it united the ‘free’ people of Anglo-Saxon England, meaning those who weren’t under Viking rule. The country would later take a giant leap towards full unification under Aethelstan, the first King of England.

Æethelred, Lord of the Mercians & The Vikings

Buckinghamshire (Photo: Allan Baxter via Getty Images)

Somewhere between 883 and 886, Alfred regained control of London, and according to his biographer – a Welsh monk called Asser – he ‘made [the city] habitable again’ after repeated Viking attacks and occupations. Alfred then handed control of the city to Aethelred.

Indeed to seal the pact between Mercia and Wessex, Aethelred married Alfred’s daughter Æthelflaed. She would later famously go on to rule Mercia after her husband became ill and died.

Over the next decade, Aethelred and Alfred spent a considerable amount of time fighting the Vikings. The most notable battles were in 893 at Thorney in modern-day Buckinghamshire and, around the same time, at the Battle of Buttington.

The Battle of Buttington pitted Danish chieftain Hastein against an alliance of Anglo-Saxon and Welsh forces led by Aethelred, Lord of the Mercians and Edward, the son of Alfred the Great. The latter managed to besiege the Viking fortifications, leaving the Viking army facing starvation. Eventually, they emerged from their fortifications, were defeated and massacred. In fact twentieth century Anglo-Saxon historian Alfred Smyth said ‘these invaders were utterly routed.’

The concerted efforts of this alliance eventually led to the establishment of the Danelaw, a region in eastern England under Viking control, with the remaining lands unified under a single English kingdom.

The Final Years of Aethelred of Mercia

Saxon cross (Photo: fotoMonkee via Getty Images)

It’s believed that somewhere between 899 and 902 (although it may have been as late as 909), Aethelred became incapacitated by illness. His duties were taken over by his wife Æthelflaed who worked alongside her brother Edward.

Aethelred died in 911, and Æthelflaed ruled as Lady of the Mercians until her death seven years later.

Both husband and wife were buried in St Oswald’s Priory in Gloucester.

While never attaining independent kingship, Æthelred’s legacy lies in his crucial role in the forging of a united Anglo-Saxon England. His strategic alliance with Alfred and his marriage to Alfred’s daughter Æthelflæd strengthened the bonds between the two kingdoms and bolstered their combined resistance against Viking invasions.

Through his leadership and collaboration with Wessex, Æthelred laid the groundwork for the eventual unification of England under Æthelstan, setting the stage for a more stable and prosperous nation.

Aethelred, The Last Kingdom

Æthelflæd, The "Lady of the Mercians" fighting (Photo: Universal History Archive via Getty Images)

The Last Kingdom is a TV show based on Bernard Cornwell’s book series “The Saxon Stories” which is set in the ninth century. Aethelred, The Last Kingdom character and his wife Aethelflaed are loosely based on the actual Anglo-Saxon rulers, but most of the stories in the TV show are works of fiction.


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