In 1013, England appeared to be collapsing remarkably efficiently.
Sweyn Forkbeard, King of Denmark, had launched an invasion that was quite different from the familiar pattern of Viking raiding. He came to conquer. Northumbria submitted, the Five Boroughs submitted, Oxford submitted and Winchester submitted. Hostages were taken and Sweyn’s army moved through England with the confidence of a force discovering that many doors were already open.
Then he reached London.
The city refused him.
The Siege of London in 1013 was one of the most important episodes in Sweyn Forkbeard’s conquest of England. King Æthelred II was inside London, supported by the formidable Viking commander Thorkell the Tall, who had entered English service with a substantial force of Scandinavian mercenaries.
The surviving account in the Anglo-Saxon Chronicle is brief, but unusually revealing. Sweyn’s troops suffered losses crossing the Thames, London resisted fiercely, and the Danish king eventually withdrew rather than take the city by direct assault.
That makes London an awkward but fascinating episode in Sweyn’s otherwise astonishingly successful campaign. He conquered England without first conquering its most important city.
Siege of London 1013 at a Glance
| Detail | Information |
|---|---|
| Conflict | Sweyn Forkbeard’s conquest of England |
| Date | 1013 |
| Location | London and the River Thames |
| Attackers | Danish invasion army under Sweyn Forkbeard |
| Defenders | Forces loyal to Æthelred II, Londoners and Scandinavian mercenaries |
| Key commanders | Sweyn Forkbeard, Æthelred II, Thorkell the Tall |
| Result at London | Sweyn failed to force the city into immediate submission |
| Wider result | Most of England subsequently recognised Sweyn |
| Strategic importance | London became one of the final centres of resistance to the Danish conquest |
The important distinction is between the fighting at London and the wider campaign. Sweyn did not simply storm London and capture it. The contemporary Chronicle states that the townsmen resisted him “with all their might”, after which he moved west.
Why Sweyn Forkbeard Invaded England
England had endured decades of Scandinavian attacks before 1013. Æthelred’s government attempted almost every solution available to an early medieval king: military mobilisation, fortification, diplomacy, tribute and the employment of Scandinavian warriors against other Scandinavians.
Results were mixed, to put it politely.
Large payments of tribute had failed to create lasting security. Political divisions within England also made coordinated resistance difficult.
Sweyn had raided England before, but his campaign of 1013 was considerably more ambitious. He was no longer simply seeking portable wealth. His movements and his systematic collection of hostages indicate a campaign aimed at political submission.
Before August 1013, Sweyn arrived at Sandwich. From there his fleet travelled around East Anglia into the Humber and then up the River Trent towards Gainsborough.
His progress was startling.
Uhtred of Northumbria submitted. Lindsey followed. So did the Five Boroughs and territories north of Watling Street. Hostages were delivered as guarantees of obedience.
Sweyn then moved south.
Oxford submitted.
Winchester submitted.
London did not.
Forces
No trustworthy contemporary source gives precise troop numbers for the fighting at London. Large numerical estimates sometimes repeated in modern accounts should therefore be treated cautiously.
We know considerably more about the composition and leadership of the opposing forces than their size.
| Force | Commander | Probable composition | Role |
| Danish invasion army | Sweyn Forkbeard | Scandinavian warriors, household retainers and campaign troops | Main invading force |
| Danish fleet | Cnut, Sweyn’s son | Ship crews and warriors | Guarded ships and hostages while Sweyn advanced |
| English royal forces | Æthelred II | Royal retainers, thegns and available English troops | Defence of London and royal authority |
| Scandinavian troops in English service | Thorkell the Tall | Experienced Viking mercenaries | Important professional element of London’s defence |
| London defenders | Civic leadership and local commanders | Armed townsmen and locally available forces | Defence of walls, gates, river approaches and bridge |
One of the great ironies of 1013 is that London’s defence against a Scandinavian king depended partly upon Scandinavian warriors.
Thorkell had previously been one of England’s most dangerous enemies. Following the payment of tribute in 1012, 45 ships entered Æthelred’s service, with the king agreeing to feed and clothe their crews.
By 1013, Thorkell was standing beside Æthelred against Sweyn.
Viking Age politics rarely rewards anyone looking for tidy teams.
Leaders
Sweyn Forkbeard
King of Denmark and father of Cnut, Sweyn was an experienced ruler and military commander.
His campaign demonstrated a sophisticated understanding of political warfare. Towns and regions were encouraged to submit and provide hostages rather than forcing Sweyn to fight for every settlement.
His objective was control of England, not the destruction of every English army.
London proved an exception.
King Æthelred II
Æthelred’s reputation has suffered enormously from his famous epithet “the Unready”. The Old English Unræd actually carries the sense of poor counsel rather than being physically unprepared.
His reign undoubtedly suffered catastrophic military and political failures, but London in 1013 provides an important corrective to the caricature of a king who simply ran away whenever Vikings appeared.
Æthelred was present in London during the resistance.
The Chronicle specifically connects the city’s refusal to surrender with the presence of Æthelred and Thorkell.
Thorkell the Tall
Thorkell is perhaps the most intriguing figure in the defence.
An experienced Scandinavian commander, he had previously campaigned violently in England before entering Æthelred’s service.
His men represented something the English desperately needed: experienced professional warriors familiar with Scandinavian warfare.
Thorkell later changed sides again and served Cnut.
Consistency was apparently not compulsory.
Cnut
The future Cnut the Great was still a young prince during his father’s campaign.
Sweyn left ships and hostages under Cnut’s control while the main army moved south. The decision suggests that Cnut already occupied a position of considerable responsibility within the invasion.
Three years later he would become king of England himself.
Troop Composition
Sweyn’s army should not be imagined as a chaotic collection of raiders charging inland from their ships.
The 1013 campaign required considerable organisation.
Sweyn’s forces probably included:
- Royal and aristocratic household warriors
- Experienced Danish and other Scandinavian fighters
- Spearmen forming the bulk of many fighting groups
- Warriors armed with swords and axes
- Archers and other missile troops
- Ship crews capable of fighting on land
- Mounted troops once horses had been acquired in England
- Commanders with experience of earlier campaigns in England
The Chronicle specifically records Sweyn ordering that his army be provisioned and provided with horses before his advance south.
That detail matters. Sweyn was transforming a seaborne invasion force into a mobile land army.
London’s defenders probably included:
- Æthelred’s household troops
- English thegns and their retainers
- Armed Londoners
- Local militia
- Thorkell’s Scandinavian mercenaries
- Archers and missile troops positioned on fortifications
- Men defending the approaches to London Bridge and the city’s gates
The defence benefited enormously from London’s physical infrastructure. Walls, gates, the river and bridge channelled attackers into predictable approaches.
Arms and Armour
The armies facing one another at London would often have looked surprisingly similar.
Scandinavian and English military cultures had been interacting for generations. Weapons crossed political boundaries rather more easily than kings did.
| Equipment | Sweyn’s army | London’s defenders |
| Spear | Extremely common | Extremely common |
| Sword | High-status sidearm | High-status sidearm |
| Dane axe / long axe | Increasingly associated with elite Scandinavian warriors | Scandinavian mercenaries may have carried similar weapons |
| Hand axe | Common utility and fighting weapon | Also used |
| Bow | Used for missile support | Useful from walls and defended positions |
| Shield | Round wooden shield with iron boss | Comparable round shields |
| Wealthier and professional warriors | Royal troops, thegns and wealthy fighters | |
| Helmet | Iron helmets among better-equipped warriors | Similar among elite defenders |
Specific Sword Types
The characteristic sword of this period was a double-edged cutting sword descended from the Carolingian and earlier Viking Age sword traditions.
Specific forms associated with the late tenth and early eleventh centuries include:
- Petersen Type H swords, a widespread Viking Age form with distinctive multi-part hilts
- Petersen Type K swords
- Petersen Type M swords, particularly associated with Scandinavian contexts
- Petersen Type X swords, representing forms increasingly common around the turn of the millennium
- Transitional swords whose simpler guards and pommels anticipate the medieval knightly sword
Blades were typically around 70 to 85 cm long, although surviving examples vary considerably.
Some blades were pattern-welded, while others were produced from increasingly sophisticated iron and steel construction. Imported or traded blades bearing inscriptions such as +VLFBERH+T belonged to a prestigious tradition, although individual examples span a broad period and should not automatically be associated with the 1013 campaign.
A sword was still an expensive possession. Most warriors probably depended primarily upon the spear.
Hollywood has done considerable damage to the spear’s reputation. Early medieval soldiers had no such prejudice.
London’s Defences
London’s greatest weapon may have been London itself.
The settlement occupied a powerful position on the Thames and retained substantial elements of the Roman defensive circuit. These had been repaired and reused during the Anglo-Saxon period.
The city offered defenders several advantages:
- Substantial defensive walls
- Restricted gates
- A major river obstacle
- London Bridge controlling an important crossing
- Dense urban development behind the fortifications
- A population capable of supplementing the garrison
- Access to river transport and supplies
- The presence of the king and Thorkell’s experienced troops
An attacking army could devastate the surrounding country, but actually entering a defended city was another matter.
Early eleventh-century Scandinavian armies were formidable in open campaigning. Breaking substantial urban fortifications without later medieval siege engines was considerably less straightforward.
Sweyn’s Approach to London
After receiving the submission of Oxford and Winchester, Sweyn turned east towards London.
The approach itself became dangerous.
The Anglo-Saxon Chronicle records that:
“much of his people was drowned in the Thames”
The chronicler adds that this occurred because they failed to keep to a bridge.
Precisely what happened is uncertain.
It may represent a failed crossing, confusion during movement beside the river, or an attempt to negotiate difficult channels without using the established crossing.
Whatever the exact circumstances, it demonstrates how London’s geography complicated Sweyn’s operations before his men had even begun serious fighting.
The Siege and Defence of London
When Sweyn reached London he encountered something he had seen remarkably little of during the later stages of the campaign: determined resistance.
The Anglo-Saxon Chronicle states:
“then would not the townsmen submit, but held out against him with all their might”
The reason given is equally important:
“because king Ethelred was therein, and Thurkill with him.”
That short passage tells us a great deal.
London’s defence was not simply a spontaneous civic uprising. The city contained the king and a substantial professional military presence.
Sweyn apparently failed to force an entry.
Exactly how long the confrontation lasted is uncertain, and describing it as a conventional later medieval siege can be misleading. There is no firm evidence for elaborate siege towers, mining operations or prolonged bombardment.
It was probably a combination of:
- Attempts to control crossings
- Pressure against defended approaches
- Skirmishing
- Missile exchanges
- Efforts to intimidate the inhabitants
- Devastation outside the walls
- Attempts to isolate the royal government
London nevertheless held.
Sweyn therefore did something strategically sensible.
He left.
Why Sweyn Abandoned the Attack
Failing to capture London did not mean Sweyn had lost the campaign.
Rather than sacrifice men against formidable defences, he moved west towards Wallingford and then crossed the Thames towards Bath.
There he received the submission of the western thegns.
The decision reveals something important about Sweyn’s strategy. London was valuable, but political control of England was more valuable.
By gathering submissions around the country he could isolate Æthelred.
Instead of taking London to conquer England, Sweyn effectively conquered England and allowed London’s resistance to become politically unsustainable.
It was a clever solution to a difficult military problem.
Æthelred Leaves England
Once the western regions submitted, Æthelred’s position became increasingly desperate.
The king eventually travelled to the Isle of Wight before leaving England for Normandy, where his wife Emma had family connections.
London ultimately submitted to Sweyn as well.
Sweyn had therefore achieved something extraordinary by the end of 1013. He had become the effective ruler of England.
Yet his triumph would last only weeks.
Archaeology and What Survives
The archaeology of the Siege of London presents a frustrating problem.
There is no securely identified destruction layer, mass grave or collection of weapons that can confidently be attributed specifically to Sweyn’s attack in 1013.
That absence matters and should not be disguised.
London has produced extensive evidence for its late Anglo-Saxon development, but separating archaeological material associated with one military episode from the enormous amount of activity taking place around 1000 is extremely difficult.
What archaeology can tell us
Evidence from Anglo-Saxon London helps reconstruct the physical environment in which the fighting occurred:
- London’s Roman walls continued to influence the city’s defensive layout.
- Late Anglo-Saxon settlement had expanded substantially within the old Roman city.
- Archaeological evidence confirms intensive occupation and craft production.
- Finds from London demonstrate extensive trade connections across England, Scandinavia and continental Europe.
- Weapons recovered from the Thames provide evidence for martial activity over a long period, although individual pieces generally cannot be connected specifically with 1013.
- Coins provide important evidence for royal administration and economic continuity during the political upheavals of Æthelred’s reign.
The temptation to label any burnt timber or Viking Age weapon “evidence of the siege” should be resisted.
Archaeology is much more interesting when we allow it to say “possibly” occasionally.
Battle Timeline
| Date | Event |
| Before August 1013 | Sweyn Forkbeard arrives at Sandwich with his fleet |
| 1013 | Sweyn sails around East Anglia and enters the Humber |
| 1013 | His forces move up the Trent to Gainsborough |
| 1013 | Uhtred and Northumbria submit |
| 1013 | Lindsey and the Five Boroughs submit |
| 1013 | Territories north of Watling Street provide hostages |
| Later 1013 | Sweyn provisions his army and obtains horses |
| Later 1013 | Cnut is left with the ships and hostages |
| Later 1013 | Sweyn marches south |
| Later 1013 | Oxford submits |
| Later 1013 | Winchester submits |
| Later 1013 | Sweyn advances towards London |
| Later 1013 | Part of his force suffers losses in the Thames |
| Later 1013 | London refuses to submit |
| Later 1013 | Æthelred and Thorkell organise resistance |
| Later 1013 | Sweyn abandons the attempt and moves towards Wallingford |
| Later 1013 | Sweyn proceeds to Bath |
| Late 1013 | Western leaders submit |
| December 1013 | Æthelred leaves England for Normandy |
| Late 1013 | London submits and Sweyn is effectively accepted as king |
| 3 February 1014 | Sweyn dies unexpectedly at Gainsborough |
| 1014 | Æthelred returns to England |
Contemporary Accounts of the Siege
Our most important source is the Anglo-Saxon Chronicle.
Its description of London’s resistance is remarkably direct:
“the townsmen… held out against him with all their might”
The chronicler explicitly associates that determination with the presence of Æthelred and Thorkell.
The Chronicle is equally uncompromising when describing Sweyn’s wider campaign. After crossing Watling Street, his army:
“wrought the most evil that any army could do.”
These are not neutral observations. The Chronicle was produced within an English Christian literary culture profoundly hostile to the devastation caused by Scandinavian armies.
Yet the basic sequence of events is clear. Sweyn’s campaign was extraordinarily successful, while London provided unusually effective resistance.
Later medieval writers expanded upon the story. Henry of Huntingdon likewise described the citizens as encouraged by Æthelred’s presence and stated that Sweyn was forced to withdraw.
Later accounts must be handled more cautiously because they were written generations after the events.
Did London Bridge Fall in 1013?
One of the most famous stories associated with Viking London concerns the destruction of London Bridge.
Norse tradition describes Olaf Haraldsson attacking a bridge defended by enemies, protecting his ships from missiles with coverings before attaching ropes to the structure and pulling it down.
It is a wonderfully cinematic story.
Unfortunately, dating it is difficult.
Later saga traditions have been associated variously with events around 1009, 1013 and 1014, and modern historians have disagreed over where the episode belongs.
Some scholarship has connected the story with Sweyn’s 1013 campaign, partly because the Chronicle’s reference to men drowning after failing to keep to a bridge is suggestive. An older study of Cnut’s reign argued that the saga episode may belong to 1013.
That remains an interpretation rather than a securely established fact.
The famous suggestion that “London Bridge is Falling Down” preserves a folk memory of a Viking attack is even more speculative.
It is a good story.
Good stories and good evidence are not always the same thing.
Why London Held
Several factors probably explain Sweyn’s failure to take the city directly.
Strong fortifications
London possessed defences considerably more formidable than those of many settlements Sweyn had encountered.
The Thames
The river protected the city while complicating troop movements and crossings.
Sweyn’s own men apparently suffered heavily in the water.
London Bridge
Control of the bridge restricted movement across the Thames and provided the defenders with a powerful fortified crossing point.
Thorkell’s warriors
Thorkell’s professional Scandinavian troops gave Æthelred an experienced fighting force capable of meeting Sweyn’s men on relatively equal terms.
Royal presence
Æthelred remained inside the city during the confrontation.
For all the criticism directed at him by later historians, that mattered. The Chronicle itself presents the king’s presence as one reason London resisted.
Was the Siege a Viking Defeat?
Tactically, yes.
Strategically, not really.
Sweyn failed to force London into submission by immediate military action. He withdrew and redirected his campaign elsewhere.
Yet within months Æthelred had fled England and Sweyn had been recognised as king.
| Measure | Outcome |
| Capture London by assault | Failed |
| Destroy Æthelred’s ability to rule England | Succeeded |
| Gain submission of major English regions | Succeeded |
| Force Æthelred into exile | Succeeded |
| Become ruler of England | Succeeded |
| Establish a lasting personal reign | Failed due to Sweyn’s death |
It is therefore misleading either to describe London as a straightforward Danish victory or to treat Sweyn’s withdrawal as a decisive English triumph.
London won the immediate confrontation.
Sweyn won the campaign.
Sweyn Forkbeard’s Sudden Death
Sweyn’s conquest proved astonishingly brief.
He died at Gainsborough on 3 February 1014, only weeks after becoming England’s effective ruler.
The circumstances remain uncertain.
His death immediately destabilised the new Danish regime. Cnut’s supporters proclaimed him king, but English political leaders invited Æthelred back.
They did so conditionally, according to the Chronicle, requiring the returning king to govern them more justly than before.
Æthelred returned.
Cnut temporarily withdrew.
England had escaped Danish conquest, but only for the moment.
From Sweyn to Cnut
The events of 1013 should be viewed as the opening act of a larger political transformation.
Sweyn demonstrated that England could be conquered.
Cnut subsequently demonstrated that it could be held.
After Æthelred died in 1016, his son Edmund Ironside fought Cnut through one of the most intense campaigns of the entire Anglo-Saxon period.
Following Edmund’s death, Cnut became undisputed king of England.
He would eventually rule a political empire encompassing England, Denmark and Norway.
The teenage prince left guarding ships and hostages in 1013 had become one of the most powerful rulers in northern Europe.
Legacy of the Siege of London
The defence of London in 1013 deserves greater attention because it complicates several familiar narratives.
Æthelred’s England was clearly in profound political difficulty, but it was not incapable of resistance.
Sweyn’s Danes were formidable, but they were not militarily unstoppable.
And London was already demonstrating the strategic characteristics that would define its importance for centuries: wealth, fortifications, population, political influence and control of the Thames.
Perhaps most interestingly, the siege shows how blurred the supposed boundary between “Viking” and “English” had become.
A Danish king attacked an English city.
An English king defended it.
And one of that English king’s most important commanders was a Scandinavian Viking who would later serve the Danish king’s son.
The eleventh century stubbornly refuses to organise itself into convenient national teams.
Frequently Asked Questions
Who won the Siege of London in 1013?
London successfully resisted Sweyn Forkbeard’s immediate attack, forcing him to move elsewhere. However, Sweyn subsequently secured the submission of most of England and London eventually accepted his rule.
Who defended London against Sweyn Forkbeard?
King Æthelred II was present in the city alongside Thorkell the Tall, whose Scandinavian mercenaries formed an important part of the defence. London’s inhabitants also participated.
Did Sweyn Forkbeard capture London?
Not by direct assault. Contemporary evidence indicates that London successfully resisted him. Sweyn instead continued his campaign elsewhere until Æthelred’s political position collapsed.
Was Cnut at the Siege of London?
Cnut participated in his father’s 1013 invasion, but the Anglo-Saxon Chronicle records that Sweyn left him responsible for the fleet and hostages before advancing south.
Did Vikings destroy London Bridge in 1013?
Possibly, but the evidence is uncertain. Later Norse tradition describes an attack on London Bridge involving Olaf Haraldsson, but scholars have disagreed about when the episode occurred.
Why was London so difficult to capture?
Its surviving Roman fortifications, controlled gates, the Thames, London Bridge, a substantial population and the presence of experienced troops all made it considerably harder to attack than an undefended settlement.
