[4][5] As the Roman occupation of Britain was coming to an end, Constantine III withdrew the remains of the army in reaction to the Germanic invasion of Gaul with the Crossing of the Rhine in December 406.

[17] It is believed that the earliest Germanic visitors were eight cohorts of Batavians attached to the 14th Legion in the original invasion force under Aulus Plautius in AD 43.

[17][18][19] There is a recent hypothesis that some of the native tribes, identified as Britons by the Romans, may have been Germanic-language speakers, but most scholars disagree with this due to an insufficient record of local languages in Roman-period artefacts.

The arrival of the Anglo-Saxons into Britain can be seen in the context of a general movement of Germanic peoples around Europe between the years 300 and 700, known as the Migration period (also called the Barbarian Invasions or Völkerwanderung).

[28] He suggested a mass immigration, with the incomers fighting and driving the sub-Roman Britons off their land and into the western extremities of the islands, and into the Breton and Iberian peninsulas.

[35][36][37][38] An emerging view is that two scenarios could have co-occurred, with large-scale migration and demographic change in the core areas of the settlement and elite dominance in peripheral regions.

Gildas records a "final" victory of the Britons at the Battle of Mount Badon in c. 500, and this might mark a point at which Anglo-Saxon migration was temporarily stemmed.

[16] But, despite the lull, the Anglo-Saxons took control of Sussex, Kent, East Anglia and part of Yorkshire; while the West Saxons founded a kingdom in Hampshire under the leadership of Cerdic, around 520.

[48] In the intervening years the Britons exhausted themselves with civil war, internal disputes, and general unrest, which was the inspiration behind Gildas's book De Excidio Britanniae (The Ruin of Britain).

[55] By convention, the Heptarchy period lasted from the end of Roman rule in Britain in the 5th century, until most of the Anglo-Saxon kingdoms came under the overlordship of Egbert of Wessex in 829.

Other minor kingdoms and territories are mentioned in sources such as the Tribal Hideage: At the end of the 6th century the most powerful ruler in England was Æthelberht of Kent, whose lands extended north to the River Humber.

[59][60] Their success was short-lived, as Oswald (one of the sons of the late King of Northumbria, Æthelfrith) defeated and killed Cadwallon at Heavenfield near Hexham.

[72] A Christian Ireland then set about evangelising the rest of the British Isles, and Columba founded a religious community in Iona, off the west coast of Scotland.

[74] Bede is very uncomplimentary about the indigenous British clergy: in his Historia ecclesiastica he complains of their "unspeakable crimes", and that they did not preach the faith to the Angles or Saxons.

The ecclesiastical writers tended to declare a territory as "converted" merely because the local king had agreed to be baptised, regardless of whether, in reality, he actually adopted Christian practices; and regardless, too, of whether the general population of his kingdom did so.

[88][89] Between the 8th and 11th centuries, raiders and colonists from Scandinavia, mainly Danish and Norwegian, plundered western Europe, including the British Isles.

[95] In March 878, the Anglo-Saxon King of Wessex, Alfred, with a few men, built a fortress at Athelney, hidden deep in the marshes of Somerset.

[97][98] There followed a peace treaty between Alfred and Guthrum, which had a variety of provisions, including defining the boundaries of the area to be ruled by the Danes (which became known as the Danelaw) and those of Wessex.

[100] After the victory at Edington and resultant peace treaty, Alfred set about transforming his Kingdom of Wessex into a society on a full-time war footing.

The Vikings were thereafter unable to cross large sections of Wessex: the Anglo-Saxon Chronicle reports that a Danish raiding party was defeated when it tried to attack the burh of Chichester.

[112] When Æthelred died in 911, Æthelflæd succeeded him as "Lady of the Mercians",[111] and in the 910s she and her brother Edward recovered East Anglia and eastern Mercia from Viking rule.

[113] Alfred's great-grandson, Edgar, who had come to the throne in 959, was crowned at Bath in 973 and soon afterwards the other British kings met him at Chester and acknowledged his authority.

[121] William of Malmesbury, writing in his Chronicle of the kings of England about one hundred years later, was scathing in his criticism of Æthelred, saying that he occupied the kingdom, rather than governed it.

[126] The system controlling the currency around the country was extremely sophisticated; this enabled the king to raise large sums of money if needed.

[133] Capitalising on his death, Æthelred returned to England and drove Sven's son, Cnut, back to Denmark, forcing him to abandon his allies in the process.

Edward is said to have wanted to fight, but at a Great Council meeting in Westminster, Earl Godwin laid down all his weapons and asked the king to allow him to purge himself of all crimes.

[147][148] On 26 December 1065, Edward was taken ill.[148] He took to his bed and fell into a coma; at one point he woke and turned to Harold Godwinson and asked him to protect the Queen and the kingdom.

[152][153][154] William was not ready to get involved so Tostig sailed from the Cotentin Peninsula, but because of storms ended up in Norway, where he successfully enlisted the help of Harald Hardrada.

[154][155] The Anglo Saxon Chronicle has a different version of the story, having Tostig land in the Isle of Wight in May 1066, then ravaging the English coast, before arriving at Sandwich, Kent.

[151][155] According to the Anglo Saxon Chronicle (Manuscripts D and E) Tostig became Hardrada's vassal and then with 300 or so longships sailed up the Humber Estuary bottling the English fleet in the river Swale and then landed at Riccall on the Ouse.