Great Heathen Army in the context of "Battle of Meretun"

Æthelred I (alt. Aethelred, Ethelred; Old English: Æthel-ræd, lit. 'noble counsel'; 845/848 to 871) was King of Wessex from 865 until his death in 871. He was the fourth of five sons of King Æthelwulf of Wessex, four of whom in turn became king. Æthelred succeeded his elder brother Æthelberht and was followed by his youngest brother, Alfred the Great. Æthelred had two sons, Æthelhelm and Æthelwold, who were passed over for the kingship on their father's death because they were still infants. Alfred was succeeded by his son, Edward the Elder, and Æthelwold unsuccessfully disputed the throne with him.

Æthelred's accession coincided with the arrival of the Viking Great Heathen Army in England. Over the next five years the Vikings conquered Northumbria and East Anglia, and at the end of 870 they launched a full-scale attack on Wessex. In early January 871, Æthelred was defeated at the Battle of Reading. Four days later, he scored a victory in the Battle of Ashdown, but this was followed by two defeats at Basing and Meretun. He died shortly after Easter. Alfred was forced to pay off the Vikings, but he scored a decisive victory over them seven years later at the Battle of Edington.

The Battle of Edington or Battle of Ethandun was fought in May 878 between the West Saxon army of King Alfred the Great and the Great Heathen Army led by the Danish warlord Guthrum. The battle took place near Edington in Wiltshire, where Alfred secured a decisive victory that halted the Viking advance into Wessex.

The engagement followed a period of sustained Danish incursions into Anglo-Saxon territory. In early 878, Guthrum launched a surprise attack on Chippenham, forcing Alfred into hiding in the marshes of Athelney. After rallying local forces, Alfred confronted and defeated Guthrum at Edington, then laid siege to the Viking position, compelling their surrender.

The Danelaw (/ˈdeɪnˌlɔː/, Danish: Danelagen; Norwegian: Danelagen; Old English: Dena lagu) was the part of England between the late ninth century and the Norman Conquest under Anglo-Saxon rule in which Danish laws applied. The Danelaw originated in the conquest and occupation of large parts of eastern and northern England by Danish Vikings in the late ninth century. The term applies to the areas in which English kings allowed the Danes to keep their own laws following the early tenth-century Anglo-Saxon conquest of Danish ruled eastern and northern England in return for the Danish settlers' loyalty to the English crown. "Danelaw" is first recorded in the early 11th century as Dena lage.

The Danelaw originated from the invasion of the Great Heathen Army into England in 865, but the term was not used to describe a geographic area until the 11th century. With the increase in population and productivity in Scandinavia, Viking warriors, having sought treasure and glory in the nearby British Isles, "proceeded to plough and support themselves", in the words of the Anglo-Saxon Chronicle for 876.

Guthrum (Old English: Guðrum, c. 835 – c. 890) was King of East Anglia in the late 9th century. Originally a native of Denmark, he was one of the leaders of the "Great Summer Army" that arrived in Reading during April 871 to join forces with the Great Heathen Army, whose intentions were to conquer the kingdoms of Anglo-Saxon England. The combined armies were successful in conquering the kingdoms of East Anglia, Northumbria, and parts of Mercia and overran Alfred the Great's Wessex but were ultimately defeated by Alfred at the Battle of Edington in 878. The Danes retreated to their stronghold, where Alfred laid siege and eventually Guthrum surrendered.

Under the terms of his surrender, Guthrum was obliged to be baptised as a Christian to endorse the agreement and then leave Wessex. The subsequent Treaty of Alfred and Guthrum set out the boundaries between Alfred and Guthrum's territories, as well as agreements on peaceful trade and the weregild value of its people. The treaty is seen as the foundation of the Danelaw. Guthrum ruled East Anglia under his baptismal name of Æthelstan until his death.

Mercia (/ˈmɜːrsiə, -ʃə/) was one of the principal kingdoms founded at the end of Sub-Roman Britain; the area was settled by Anglo-Saxons in an era called the Heptarchy. It was centred on the River Trent and its tributaries, in a region now known as the Midlands of England.

The royal court moved around the kingdom without a fixed capital city. Early in its existence Repton seems to have been the location of an important royal estate. According to the Anglo-Saxon Chronicle, it was from Repton in 873–874 that the Great Heathen Army deposed the King of Mercia. Slightly earlier, King Offa seems to have favoured Tamworth. It was there where he was crowned, and where he resided during multiple Christmases.

The Kingdom of the East Angles, informally known as the Kingdom of East Anglia, was a small independent kingdom of the Angles during the Anglo-Saxon period comprising what are now the English counties of Norfolk and Suffolk and perhaps the eastern part of the Fens; the area still known as East Anglia.

The kingdom formed in the 6th century in the wake of the Anglo-Saxon settlement of Britain and was one of the kingdoms of the Heptarchy. It was ruled by the Wuffingas dynasty in the 7th and 8th centuries, but the territory was taken by Offa of Mercia in 794. Mercian control lapsed briefly following the death of Offa but was reestablished. The Danish Great Heathen Army landed in East Anglia in 865; after taking York it returned to East Anglia, killing King Edmund ("the Martyr") and making it Danish land in 869. After Alfred the Great forced a treaty with the Danes, East Anglia was left as part of the Danelaw.

Athelney is a village located between the villages of Burrowbridge and East Lyng in Somerset, England. The name is believed to be derived from the Old English æþeling meaning "prince" + -ey meaning "isle". The village is best known for once being the fortress hiding place of King Alfred the Great, from where he went on to defeat the Great Heathen Army at the Battle of Edington in May 878.