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.
Viking raid warfare and tactics
In Northern Europe at the start of the 8th century, Vikings began raiding coasts of the British Isles across the sea from Scandinavia, particularly monasteries, which carried a great deal of valuable treasures. The first known raid was on the Holy Island of Lindisfarne off the English coast in 793. This raid was also the first one that made a lasting impact on the British Isles and made the Anglo-Saxons aware of the Viking threat. A primary source from the raid on Lindisfarne states that there "were immense flashes of lightning, and fiery dragons were seen flying in the air". These raids continued for the entirety of the Viking Age. These initial raids had a religious implication to them. Vikings would target monasteries along the coast, raid the towns for their booty, and destroy what was left. This caused mass fear amongst such monks, as they felt that it was punishment from God. There is also the complication of a lack of direct written sources about these raids from the Viking perspective. This leads to biased views of the raiders from Christians who were being attacked in their churches and lands . From their point of view, the Vikings were violent and evil heathens.