Early Scandinavian Dublin
In the year 795 Vikings (probably of Norwegian origin) raided islands off the coast of Ireland for the first time. This was the beginning of a new phase of Irish history, which saw many native communities – particularly ecclesiastical ones – relocate themselves on the continent, or further afield in places like Iceland and the Faroe Islands, to escape the pagan marauders. For about two decades the invaders confined their activities to coastal settlements; raiding parties were generally small and there is no evidence that any of them wintered in Ireland during this early phase of "hit-and-run" activity. Typically the Vikings would arrive at a settlement without warning, plunder what goods and people they could – the people were usually sold as slaves, though notable personages were often held for ransom – before retreating to their Scandinavian or British bases. This period lasted from 795 until 813, after which there occurred a hiatus of eight years.
It is now thought that these early raids were launched directly from southwest Norway, and that during the period of calm (814–820) the Norwegian Vikings were occupied in northern Britain, laying the foundations of a new kingdom referred to in Irish sources as Laithlind (later Lochlainn). Laithlind was once thought to be in Norway but it is now identified with Viking settlements in the British Isles, especially those in Scotland and the Isle of Man.
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.