The first Viking raid on Anglo-Saxon England is thought to have occurred between 786 and 802 at Portland in the Kingdom of Wessex, when three Norse ships arrived; their men killed King Beorhtric's reeve.

[3] This year dire forwarnings came over the land of the Northhumbrians, and miserably terrified the people; these were excessive whirlwinds, and lightnings; and fiery dragons were seen flying in the air.

[9] Alfred the Great had spent the winter preceding the Battle of Edington in the Somerset marsh of Athelney, protected somewhat by the natural defences of the country.

[10] In the spring of 878, he summoned his West Saxon forces and marched to Edington, where he met the Danes, led by Guthrum, in battle.

[11] Guthrum and his men had adopted the usual Danish strategy of occupying a fortified town and waiting for a peace treaty, involving money in return for a promise to leave the kingdom immediately.

The fact that his army could not defend the fortified Chippenham, even in "an age... as yet untrained in siege warfare"[13] casts great doubt on its ability to defeat the Danes in an open field, unaided by fortifications.

With his small warband, a fraction of his army at Chippenham, Alfred could not hope to retake the town from the Danes, who had in previous battles (for example at Reading in 871) proved themselves adept at defending fortified positions.

According to the Life: "Fighting ferociously, forming a dense shield-wall against the whole army of the Pagans, and striving long and bravely...at last he [Alfred] gained the victory.

[18] After two weeks, the starving Danes sued for peace, giving Alfred "preliminary hostages and solemn oaths that they would leave his kingdom immediately", just as usual, but in addition promising that Guthrum would be baptized.

The men of even one shire could be a formidable fighting force, as those of Devon proved in the same year, defeating an army under Ubba at the Battle of Cynwit.

The primary sources for the location of the battle are Asser's Life of King Alfred, which names the place as "Ethandun" and the Anglo-Saxon Chronicle, which has Eðandun.

[25] A version of the Life, written in about 1000 and known as the Cotton Otho A. xii text, lasted until 1731, when it was destroyed in the fire at Ashburnham House.

[27] In 1904 William Henry Stevenson analysed possible sites and said "So far, there is nothing to prove the identity of this Eðandun [as named in the Anglo-Saxon Chronicle] with Edington" but then goes on to say that "there can be little reason for questioning it".

[28][29] The reasoning to support the Eðandun of the Anglo-Saxon Chronicle and the Ethandun of Asser's Life being Edington in Wiltshire is derived from a trail of information from ancient manuscripts.

The Tudor historian Polydore Vergil appears to have misread the ancient texts for the battle site, as he places it at Abyndoniam (Abingdon) instead of Edington.

[24][47] It is possible that the enforced conversion was an attempt by Alfred to lock Guthrum into a Christian code of ethics, hoping it would ensure the Danes' compliance with any treaties agreed to.

[48] In 885 Asser reports that the Viking army that had settled in East Anglia had broken in a most insolent manner the peace they had established with Alfred, although Guthrum is not mentioned.

[55] It is not clear how seriously Guthrum took his conversion to Christianity, but he was the first of the Danish rulers of the English kingdoms to mint coins on the Alfredian model, under his baptismal name of Athelstan.

[55] After the defeat of Guthrum at the Battle of Edington, Alfred's reforms to military obligations in Wessex made it increasingly difficult for the Vikings to raid successfully.

However, the system of military reforms and the Burghal Hidage introduced by Edward the Elder enabled Alfred's successors to retake control of the lands occupied in the North of England by the Danes.