Vikings in Iberia
The first incursion of the Vikings in Iberia has been characterised as 'probably the most significant episode of the whole period of Viking activity in the South'. It is mentioned in "Annales Bertiniani", and dated August 844, when a group from a plundering expedition entered the Garonne and reached Galicia. Despite storm damage, some proceeded to South-West Spain. This account is consistent with several later, but independent sources in Latin and Arabic. In particular, the late ninth- or early tenth-century "Chronicle of Alfonso III" adds that after plundering a number of coastal villages they were ultimately repulsed in the vicinity of "Farum Brecantium" (i.e. the Tower of Hercules). Ramiro I of Asturias gathered troops in Galicia and Asturia for the counter-attack. After the Asturian victory, the Vikings continued their voyage in direction of Lisbon. While some authors consider that the reliability of this chronicle is open to doubt, others consider that other local chronicles confirm the arrival of the Norsemen.
Norse activity in the British Isles
The first known account of a Viking raid taking place in Anglo-Saxon England comes from 787, when three ships from Hordaland (in modern Norway) landed in the Isle of Portland on the southern coast of Wessex. They were approached by the royal reeve from Dorchester, whose job it was to identify all foreign merchants entering the kingdom, and they proceeded to kill him. It is likely that other raids (the records for which have since been lost) occurred soon after, for in 792 King Offa of Mercia began to make arrangements for the defence of Kent from raids perpetrated by "pagan peoples".