The early Anglo-Saxon period covers the history of medieval Britain that starts from the end of Roman rule. It is a period widely known in European history as the Migration Period, also the Völkerwanderung ("migration of peoples" in German). This was a period of intensified human migration in Europe from about 375 to 800. The migrants were Germanic tribes such as the Goths, Vandals, Angles, Saxons, Lombards, Suebi, Frisii, and Franks; they were later pushed westwards by the Huns, Avars, Slavs, Bulgars, and Alans. The migrants to Britain might also have included the Huns and Rugini. Until CE 400, Roman Britain, the province of Britannia, was an integral, flourishing part of the Western Roman Empire, occasionally disturbed by internal rebellions or barbarian attacks, which were subdued or repelled by the large contingent of imperial troops stationed in the province. By 410, however, the imperial forces had been withdrawn to deal with crises in other parts of the empire, and the Romano-Britons were left to fend for themselves in what is called the post-Roman or "sub-Roman" period of the 5th century.

The end of Roman rule in Britain was the transition from Roman Britain to post-Roman Britain. Roman rule ended in different parts of Britain at different times, and under different circumstances. In 383, the usurper Magnus Maximus withdrew troops from northern and western Britain, probably leaving local warlords in charge. Around 410, the Romano-British expelled the magistrates of the usurper Constantine III. He had previously stripped the Roman garrison from Britain and taken it to Gaul in response to the Crossing of the Rhine in late 406, leaving the island a victim to barbarian attacks. Roman Emperor Honorius replied to a request for assistance with the Rescript of Honorius, telling the Roman cities to see to their own defence, a tacit acceptance of temporary British self-government. Honorius was fighting a large-scale war in Italy against the Visigoths under their leader Alaric, with Rome itself under siege. No forces could be spared to protect distant Britain. Though it is likely that Honorius expected to regain control over the provinces soon, by the mid-6th century Procopius recognised that Roman control of Britannia was entirely lost.

The emergence of Anglo-Saxon culture in Britain, beginning with the decline of Roman rule around 400 CE, marked a transformative period in British history. Rather than simply transplanting Germanic culture from northern Europe, the Anglo-Saxon identity developed within Britain itself, blending local and migrant traditions.

By the late Roman period, Germanic-speaking peoples, such as the Saxons, were both allies and threats to the empire. Roman sources describe Saxon raids on the North Sea coasts, prompting the construction of coastal defenses known as the Saxon Shore forts. Simultaneously, Germanic mercenaries, known as foederati, were recruited to bolster the dwindling Roman military presence.

In the early 5th century, political turmoil escalated. Constantine III, a usurper emperor based in Britain, led Roman forces to the continent, leaving Britain vulnerable. Following his fall in 411, Roman authority in Britain collapsed. According to Gildas, writing in the 6th century, a "proud tyrant" (later named by Bede as Vortigern) invited Saxon mercenaries to defend against raids by Picts and Scots. The Saxons later turned on their hosts, sparking conflict and migration.

By the mid-5th century, Germanic settlers—Angles, Saxons, and Jutes—began to establish themselves in Britain. Archaeological evidence suggests this process started earlier than traditional accounts, such as those of Bede, who dated it to around 450 CE. Studies of burial sites, such as Spong Hill, point to migrations occurring as early as the late 4th century.

The Saxons settled in southern and southeastern England, including Wessex, Sussex, and Essex. The Jutes occupied Kent and the Isle of Wight, while the Angles settled in regions that became East Anglia, Mercia, and Northumbria. These groups hailed from various regions of northern Europe, including Old Saxony, Jutland, and Angeln.

Gildas describes a war between the Britons and Saxons, culminating in a Romano-British victory at Mons Badonicus, led by the enigmatic figure Ambrosius Aurelianus. However, by the 6th century, archaeological evidence indicates that Anglo-Saxon culture had become dominant in much of lowland Britain. Historians debate whether this reflects conquest or the widespread adoption of Anglo-Saxon culture by native Britons.

Bede, writing in the 8th century, portrayed the Anglo-Saxon settlement as a decisive migration and conquest, but his account relied heavily on earlier sources like Gildas and incorporated legendary elements. Modern historians suggest a more complex process, involving both conflict and cultural assimilation.

Apart from Gildas, contemporary written records are scarce. Later sources, such as the Anglo-Saxon Chronicle and Historia Brittonum, provide details but are often unreliable for this period. Procopius, a Byzantine historian, reported that Britain was divided between Britons, Angles, and Frisians in the 6th century, suggesting a mix of local and migrant populations.

The Battle of Badon (also called Mons Badonicus) is a pivotal event in early British history, traditionally dated to the late 5th or early 6th century CE. This battle is described as a major victory for the Romano-British against Anglo-Saxon invaders during the chaotic post-Roman period. Despite its importance, the details of the battle remain obscure, as accounts from the time are sparse and often contradictory.

The most detailed early reference comes from Gildas, a 6th-century British monk. In his work De Excidio et Conquestu Britanniae, Gildas describes the battle as the culmination of a long period of warfare between the Britons and Anglo-Saxons. He attributes the British victory to divine intervention and credits a Romano-British leader—likely Ambrosius Aurelianus, whom he calls "the last of the Romans"—as a key figure in rallying the British forces. However, Gildas does not name the location of the battle or provide specific details, such as the identity of the Saxon leaders.

The historical context of the battle aligns with a period of Anglo-Saxon migration and conflict in Britain following the collapse of Roman rule around 410 CE. The Britons, struggling to maintain their territory, likely fought to halt Saxon expansion into the western and northern parts of the island.

The battle’s location remains uncertain, with suggested sites ranging from southern England to the Severn Valley or even near modern-day Bath. The term "Badon" may refer to a hill or fortified place, but no definitive archaeological evidence has been found to confirm the exact site.

Gildas portrays the battle as a decisive British victory that brought peace and a temporary halt to Saxon expansion. This period of relative stability lasted for several decades, providing a brief respite for the Romano-British kingdoms. However, the eventual resurgence of the Anglo-Saxons in the 6th and 7th centuries led to their dominance over much of England.

In the last half of the 6th century, four structures contributed to the development of society:

1. the position and freedoms of the ceorl
2. the smaller tribal areas coalescing into larger kingdoms
3. the elite developing from warriors to kings
4. Irish monasticism developing under Finnian (who had consulted Gildas) and his pupil Columba.

The Anglo-Saxon farms of this period are often falsely supposed to be "peasant farms". However, a ceorl, who was the lowest ranking freeman in early Anglo-Saxon society, was not a peasant but an arms-owning male with the support of a kindred, access to law and the wergild; situated at the apex of an extended household working at least one hide of land. The farmer had freedom and rights over lands, with provision of a rent or duty to an overlord who provided only slight lordly input. Most of this land was common outfield arable land (of an outfield-infield system) that provided individuals with the means to build a basis of kinship and group cultural ties.

Augustine landed on the Isle of Thanet and proceeded to King Æthelberht's main town of Canterbury. He had been the prior of a monastery in Rome when Pope Gregory the Great chose him in 595 to lead the Gregorian mission to Britain to Christianise the Kingdom of Kent from their native Anglo-Saxon paganism. Kent was probably chosen because Æthelberht had married a Christian princess, Bertha, daughter of Charibert I the king of Paris, who was expected to exert some influence over her husband. Æthelberht was converted to Christianity, churches were established, and wider-scale conversion to Christianity began in the kingdom.

The Kingdom of Northumbria was a prominent Anglo-Saxon kingdom in northern England and southeastern Scotland from the 7th to the 10th centuries. Formed through the unification of the earlier kingdoms of Bernicia and Deira around 604 CE, Northumbria became a major cultural, religious, and military power during the Anglo-Saxon period.

Northumbria's early strength lay in its powerful rulers, such as Æthelfrith of Bernicia, who unified the kingdom, and Edwin of Northumbria, who expanded its influence. Edwin's conversion to Christianity in 627, under the guidance of Saint Paulinus, established Northumbria as a religious center. The kingdom’s golden age began under Oswald (r. 634–642) and his successor Oswiu (r. 642–670), who extended Northumbrian supremacy over much of England.

Northumbria became a hub of Christian learning and culture. The monastery of Lindisfarne, founded in 635, and the Synod of Whitby (664), which aligned the kingdom with Roman Christianity, were pivotal in shaping English religious history. Monasteries like Jarrow and Wearmouth produced scholars like Bede, whose "Ecclesiastical History of the English People" is a key source for early English history.

Northumbria’s power waned in the 8th century due to internal strife and external threats, including Mercian aggression. Viking invasions in the late 8th and 9th centuries, beginning with the raid on Lindisfarne in 793, further destabilized the kingdom. By the mid-9th century, Norse forces captured much of Northumbria, including its capital, York, which became the Viking-ruled Kingdom of Jórvík.

By the 10th century, Northumbria had fragmented, with its southern territories under English control and the north often influenced by Norse rulers. The kingdom was formally incorporated into a unified England under King Æthelstan after his victory at the Battle of Brunanburh in 937.

Northumbria’s legacy lies in its contributions to early medieval English culture, religion, and scholarship. Despite its decline, its role in uniting Bernicia and Deira and its achievements in Christian learning left a lasting impact on Anglo-Saxon England.

Mercian Supremacy was the period during the 7th to 9th centuries when the Kingdom of Mercia was the dominant power among the Anglo-Saxon kingdoms of England. This era marked the height of Mercian influence in the political and military affairs of early medieval England, driven by strong rulers and strategic expansion.

Mercia, located in the English Midlands, emerged as a significant kingdom in the 7th century under kings like Penda (r. 626–655), a pagan who resisted the spread of Christianity and defeated neighboring kingdoms, including Northumbria. However, his defeat and death at the Battle of Winwaed (655) temporarily weakened Mercia.

Mercian dominance resumed under later kings, particularly Wulfhere (r. 658–675) and Æthelred (r. 675–704), who expanded their territory and influence. The kingdom grew into a formidable power through alliances, military conquests, and control of trade routes along the River Thames and beyond.

Mercian Supremacy reached its zenith under King Offa (r. 757–796). Offa established Mercia as the preeminent Anglo-Saxon kingdom, extending his influence over Wessex, Kent, East Anglia, and Northumbria. He is best known for constructing Offa’s Dyke, a massive earthwork along the Welsh border, and for fostering international trade and diplomacy, including ties with Charlemagne. Offa's reign also saw the creation of a unified currency system, with coins like the silver penny, which standardized trade across England.

After Offa’s death, Mercia struggled to maintain its dominance. Internal instability and the rise of Wessex as a competing power under leaders like Egbert (r. 802–839) eroded Mercian influence. The decisive blow came in 825 at the Battle of Ellandun, where Wessex defeated Mercia, marking the end of its supremacy. Viking invasions further weakened Mercia, with the kingdom losing significant territory to the Danelaw in the 9th century.

The Heptarchy refers to the traditional idea of Anglo-Saxon England being divided into seven main kingdoms—East Anglia, Essex, Kent, Mercia, Northumbria, Sussex, and Wessex—from the 6th to 8th centuries. This term, coined by the 12th-century historian Henry of Huntingdon, has since been used to describe this era despite its inaccuracies. The number of kingdoms and political entities during this time was far more fluid, with the actual power dynamics shifting frequently.

In the 6th century, Kent emerged as a leading kingdom in the south due to its ties to the Frankish world and early adoption of Christianity. The 7th century saw the rise of Northumbria in the north and Wessex in the south as dominant powers. By the 8th century, Mercia became the preeminent kingdom, particularly under the rule of Offa the Great (757–796), who wielded considerable influence over much of England.

The term "heptarchy" simplifies a more complex political landscape. Besides the primary seven kingdoms, there were numerous smaller entities and sub-kingdoms, such as:

• Bernicia and Deira, which formed Northumbria.
• Lindsey, in what is now Lincolnshire.
• The Hwicce, in the southwest Midlands.
• Magonset, a sub-kingdom of Mercia in modern Herefordshire.
• Wihtwara, a Jutish kingdom on the Isle of Wight.
• Middle Angles, in present-day Leicestershire, later absorbed by Mercia.
• Hæstingas, near modern Hastings in Sussex.
• The Gewisse, who were ancestors of the West Saxons in Wessex.

By the 8th century, the period of smaller, competitive kingdoms waned as regional consolidation occurred. Mercia, Northumbria, Wessex, and East Anglia emerged as the dominant powers, signaling the decline of the Heptarchy framework. Over time, these larger kingdoms vied for supremacy, culminating in the unification of England under Wessex in the 9th and 10th centuries during the struggle against Viking invasions.

Anglo-Saxon monasticism developed the unusual institution of the "double monastery", a house of monks and a house of nuns, living next to each other, sharing a church but never mixing, and living separate lives of celibacy. These double monasteries were presided over by abbesses, who became some of the most powerful and influential women in Europe. Double monasteries which were built on strategic sites near rivers and coasts, accumulated immense wealth and power over multiple generations (their inheritances were not divided) and became centers of art and learning. While Aldhelm was doing his work in Malmesbury, far from him, up in the North of England, Bede was writing a large quantity of books, gaining a reputation in Europe and showing that the English could write history and theology, and do astronomical computation (for the dates of Easter, among other things).

A Viking raid on Lindisfarne caused much consternation throughout the Christian west and is now often taken as the beginning of the Viking Age. There had been some other Viking raids, but according to English Heritage this one was particularly significant, because "it attacked the sacred heart of the Northumbrian kingdom, desecrating ‘the very place where the Christian religion began in our nation’".

The West Saxon hegemony emerged during the later stages of the Anglo-Saxon period (5th–11th centuries CE) and marked the dominance of Wessex among the Anglo-Saxon kingdoms in England. This hegemony was a significant turning point, as it laid the foundation for the unification of England.

The Anglo-Saxons, a mix of Germanic tribes (Angles, Saxons, and Jutes), began settling in Britain after the Roman withdrawal in the 5th century. Over time, they formed several independent kingdoms, collectively known as the Heptarchy: Northumbria, Mercia, East Anglia, Essex, Sussex, Kent, and Wessex. These kingdoms vied for power, with dominance shifting between them.

Britain Isles in 802. © Lotroo

Initially, Northumbria and Mercia were the leading powers. In the 7th and 8th centuries, Mercia often held sway under rulers like Offa. However, the rise of Wessex began in the late 8th century under kings such as Egbert (r. 802–839). Egbert extended Wessex’s influence through military victories, including his decisive defeat of Mercia at the Battle of Ellandun in 825, which ended Mercian supremacy. Egbert's successors continued to consolidate power.

The Viking invasions of the late 8th and 9th centuries significantly altered the political landscape. Many Anglo-Saxon kingdoms succumbed to the Danes, leaving Wessex as the primary bastion of resistance. King Alfred the Great (r. 871–899) emerged as a key figure during this period, successfully defending Wessex against Viking incursions, notably at the Battle of Edington in 878. Alfred implemented military reforms, constructed a network of fortified towns (burhs), and negotiated the Treaty of Wedmore, which established the Danelaw, dividing England into Danish and Anglo-Saxon territories.

Under Alfred’s successors, Wessex expanded its influence. His son Edward the Elder and grandson Æthelstan achieved further consolidation. Æthelstan’s victory at the Battle of Brunanburh in 937 effectively established him as the first king of a unified England. Wessex’s dominance continued under subsequent rulers, with the West Saxon royal house forming the foundation of the English monarchy.

The West Saxon hegemony was crucial in shaping the political and cultural identity of England. It provided stability during a turbulent era and ensured the survival of Anglo-Saxon traditions until the Norman Conquest of 1066.

The Battle of Ellendun or Battle of Wroughton was fought between Ecgberht of Wessex and Beornwulf of Mercia in September 825. Sir Frank Stenton described it as "one of the most decisive battles of English history". It effectively ended Mercian Supremacy over the southern kingdoms of Anglo-Saxon England and established West Saxon dominance in southern England.

The Great Heathen Army, also known as the Viking Great Army, was a coalition of Scandinavian warriors who invaded England in 865 CE. Unlike earlier Viking raids targeting wealth centers like monasteries, this invasion aimed to conquer and occupy the Anglo-Saxon kingdoms of East Anglia, Northumbria, Mercia, and Wessex. The invasion was led by three sons of the legendary Ragnar Lodbrok: Ivar the Boneless, Halfdan Ragnarsson, and Ubba, and lasted for 14 years.

Great Heathen Army map. © Hel-hama

The army landed in East Anglia, where they secured horses in exchange for peace, before capturing York in 866. By 867, they had established control in Northumbria and moved into Mercia, forcing local rulers to pay tribute. In 869, the Vikings conquered East Anglia and killed its king, Edmund, later venerated as a martyr. By 871, the Vikings turned their attention to Wessex, where Alfred the Great initially paid them to leave. They later defeated Mercia, exiling its king in 874 and dividing the army, with some settling in Northumbria and East Anglia, forming what would become the Danelaw.

Alfred decisively defeated the Vikings at the Battle of Edington in 878, leading to the Treaty of Wedmore. This agreement allowed the Vikings to retain control of northern and eastern England while Alfred fortified Wessex with a system of burhs and reorganized his military, ensuring the kingdom's defense against future attacks.

The Great Heathen Army's campaigns reshaped Anglo-Saxon England, establishing Viking-controlled regions and accelerating the political unification efforts that eventually led to the formation of England.

More important to Alfred than his military and political victories were his religion, his love of learning, and his spread of writing throughout England. Keynes suggests Alfred's work laid the foundations for what really made England unique in all of medieval Europe from around 800 until 1066. This began a growth in charters, law, theology and learning. Alfred thus laid the foundation for the great accomplishments of the tenth century and did much to make the vernacular more important than Latin in Anglo-Saxon culture.

At first, Alfred responded by the offer of repeated tribute payments to the Vikings. However, after a decisive victory at Edington in 878, Alfred offered vigorous opposition. He established a chain of fortresses across the south of England, reorganised the army, "so that always half its men were at home, and half out on service, except for those men who were to garrison the burhs", and in 896 ordered a new type of craft to be built which could oppose the Viking longships in shallow coastal waters.

When the Vikings returned from the Continent in 892, they found they could no longer roam the country at will, for wherever they went they were opposed by a local army. After four years, the Scandinavians therefore split up, some to settle in Northumbria and East Anglia, the remainder to try their luck again on the Continent.

Æthelstan, often hailed by modern historians as the first King of England, is considered a significant figure in the West Saxon dynasty, although his accomplishments were long overshadowed by his grandfather, Alfred the Great. Noted for his just and learned rule, Æthelstan's governance was admired by contemporary and later chroniclers alike, with William of Malmesbury praising him highly. Scholars like Simon Keynes and Frank Stenton regard Æthelstan as comparable to Alfred, emphasizing his central role in establishing the concept of a unified England.

Despite not achieving the permanent conquest of Viking York—a feat accomplished by his successors—Æthelstan's military campaigns were foundational in making such achievements possible. His governance laid the groundwork for the centralized government and legal reforms seen later in the Anglo-Saxon period. This included the creation of a highly organized administrative system that would be further developed by his successors. Æthelstan also continued his grandfather’s ecclesiastical policies, strengthening the church's role in England and laying the groundwork for monastic reforms later in the century. He was deeply respected in his lifetime, celebrated as a military leader, a devout king, and a patron of learning and religion.

However, his memory waned after his death, with later generations focusing more on Alfred the Great. It was not until William of Malmesbury in the twelfth century that Æthelstan's achievements were revisited in historical accounts. His reputation saw fluctuating interest over the centuries, largely absent in popular consciousness and significantly overshadowed by Alfred until scholarly revival in the eighteenth and nineteenth centuries. Overall, Æthelstan's reign marked a pivotal moment in early medieval England, establishing precedents in governance, law, and ecclesiastical organization that would influence the subsequent development of the English state.

Viking raids resumed on England, putting the country and its leadership under strains as severe as they were long sustained. Raids began on a relatively small scale in the 980s but became far more serious in the 990s, and brought the people to their knees in 1009–12, when a large part of the country was devastated by the army of Thorkell the Tall. It remained for Sweyn Forkbeard, king of Denmark, to conquer the kingdom of England in 1013–14, and (after Æthelred's restoration) for his son Cnut to achieve the same in 1015–16.

The Battle of Maldon took place on 11 August 991 CE near Maldon beside the River Blackwater in Essex, England, during the reign of Æthelred the Unready. Earl Byrhtnoth and his thegns led the English against a Viking invasion. The battle ended in an Anglo-Saxon defeat. After the battle Archbishop Sigeric of Canterbury and the aldermen of the south-western provinces advised King Æthelred to buy off the Vikings rather than continue the armed struggle. The result was a payment of 10,000 Roman pounds (3,300 kg) of silver, the first example of Danegeld in England.

The Battle of Assandun ended in victory for the Danes, led by Cnut the Great, who triumphed over the English army led by King Edmund Ironside. The battle was the conclusion to the Danish reconquest of England. Cnut ruled England for nearly two decades. The protection he lent against Viking raiders—many of them under his command—restored the prosperity that had been increasingly impaired since the resumption of Viking attacks in the 980s. In turn the English helped him to establish control over the majority of Scandinavia, too.

The Norman Conquest of 1066 marked the end of the Anglo-Saxon era and the beginning of a new chapter in English history. It followed centuries of Anglo-Saxon rule and culture, during which England had been shaped by waves of Germanic settlement, the rise and fall of kingdoms, the consolidation of power under Wessex, and the ongoing challenge of Viking incursions. The conquest abruptly replaced the Anglo-Saxon elite with Norman rulers, bringing profound political, social, and cultural changes.

The Anglo-Saxon period concluded under Edward the Confessor (r. 1042–1066), a king with strong Norman ties. Edward's death without an heir in January 1066 triggered a succession crisis. The Anglo-Saxon noble Harold Godwinson claimed the throne, but his claim was contested by two powerful rivals: William, Duke of Normandy, and Harald Hardrada, King of Norway.

In September 1066, Harold defeated Harald Hardrada at the Battle of Stamford Bridge, but he faced a greater challenge shortly after. William invaded England with a well-prepared Norman force, landing in Sussex and forcing Harold to march south.

On October 14, 1066, Harold's army met William's at the Battle of Hastings. The Normans, using superior cavalry tactics and feigned retreats, overwhelmed the Anglo-Saxon forces. Harold was killed, likely by an arrow to the eye, and his army was destroyed. William swiftly moved to secure his claim, being crowned King of England on Christmas Day, 1066.

The Norman Conquest dismantled the existing Anglo-Saxon ruling structure. William confiscated vast estates from the Anglo-Saxon nobility, redistributing them to Norman lords. This led to the near-total displacement of the Anglo-Saxon elite. Norman innovations, including the feudal system, transformed governance and land ownership, centralizing power around the crown.

The Normans also introduced new cultural and linguistic influences. Old English was replaced by Anglo-Norman as the language of the court and administration, deeply influencing the development of Middle English. Norman architecture, exemplified by castles and cathedrals, reshaped the English landscape.

The Conquest also marked a shift in England's geopolitical focus. Ties to Scandinavia, prominent during the Viking Age, diminished, while connections to Normandy and continental Europe grew stronger.

The Norman Conquest ended nearly 600 years of Anglo-Saxon rule, which had seen the formation of England as a unified kingdom, the flourishing of Old English culture, and the resilience of the English people through invasions and upheavals. Although the Anglo-Saxon legacy endured in language, law, and customs, the Conquest irrevocably altered England's trajectory, integrating it into a broader European framework and laying the foundations for the medieval English monarchy.

Following the Norman conquest, many of the Anglo-Saxon nobility were either exiled or had joined the ranks of the peasantry. It has been estimated that only about 8% of the land was under Anglo-Saxon control by 1087. In 1086, only four major Anglo-Saxon landholders still held their lands. However, the survival of Anglo-Saxon heiresses was significantly greater. Many of the next generation of the nobility had English mothers and learnt to speak English at home.

Some Anglo-Saxon nobles fled to Scotland, Ireland, and Scandinavia. The Byzantine Empire became a popular destination for many Anglo-Saxon soldiers, as it was in need of mercenaries. The Anglo-Saxons became the predominant element in the elite Varangian Guard, hitherto a largely North Germanic unit, from which the emperor's bodyguard was drawn and continued to serve the empire until the early 15th century. However, the population of England at home remained largely Anglo-Saxon; for them, little changed immediately except that their Anglo-Saxon lord was replaced by a Norman lord.