In the final decade of the eighth century, Viking raiders attacked a series of Christian monasteries in the British Isles. Here, these monasteries had often been positioned on small islands and in other remote coastal areas so that the monks could live in seclusion, devoting themselves to worship without the interference of other elements of society. At the same time, it made them isolated and unprotected targets for attack.

The first known account of a Viking raid in Anglo-Saxon England comes from 789, when three ships from Hordaland (in modern Norway) landed in the Isle of Portland on the southern coast of Wessex. They were approached by Beaduheard, the royal reeve from Dorchester, whose job it was to identify all foreign merchants entering the kingdom, and they proceeded to kill him. There were almost certainly unrecorded earlier raids. In a document dating to 792, King Offa of Mercia set out privileges granted to monasteries and churches in Kent, but he excluded military service "against seaborne pirates with migrating fleets", showing that Viking raids were already an established problem. In a letter of 790-92 to King Æthelred I of Northumbria, Alcuin berated English people for copying the fashions of pagans who menaced them with terror. This shows that there were already close contacts between the two peoples, and the Vikings would have been well informed about their targets.

The next recorded attack against the Anglo-Saxons came the following year, in 793, when the monastery at Lindisfarne, an island off England's eastern coast, was sacked by a Viking raiding party on 8 June. The following year, they sacked the nearby Monkwearmouth–Jarrow Abbey.In 795, they once again attacked, this time raiding Iona Abbey off Scotland's west coast.This monastery was attacked again in 802 and 806, when 68 people living there were killed. After this devastation, the monastic community at Iona abandoned the site and fled to Kells in Ireland. In the first decade of the ninth century, Viking raiders began to attack coastal districts of Ireland. In 835, the first major Viking raid in southern England took place and was directed against the Isle of Sheppey.