Vikings
In England the Viking Age began dramatically on 8 June 793 when Norsemen destroyed the abbey on the island of Lindisfarne. The devastation of Northumbria's Holy Island shocked and alerted the royal courts of Europe to the Viking presence. "Never before has such an atrocity been seen," declared the Northumbrian scholar Alcuin of York. Medieval Christians in Europe were totally unprepared for the Viking incursions and could find no explanation for their arrival and the accompanying suffering they experienced at their hands save the "Wrath of God". More than any other single event, the attack on Lindisfarne demonised perception of the Vikings for the next twelve centuries. Not until the 1890s did scholars outside Scandinavia begin to seriously reassess the achievements of the Vikings, recognizing their artistry, technological skills, and seamanship.
History of Ireland
The Vikings were expert sailors, who travelled in longships, and by the early 840s, had begun to establish settlements along the Irish coasts and to spend the winter months there. The longships were technologically advanced, allowing them to travel faster through the narrow rivers. Vikings founded settlements in several places; most famously in Dublin. Most of the settlements were near the water, allowing the Vikings to trade using their longships. Written accounts from this time (early to mid 840s) show that the Vikings were moving further inland to attack (often using rivers) and then retreating to their coastal headquarters.