The Northmen are often said to have burst out of their coastal settlements in what is now Sweden, Norway, and Denmark at the end of the eighth century. The most famous account of their arrival into the Christian realms of the west comes from Britain. In 793 warriors appeared off the coast of Northumbria, leaped from their ships, and robbed the island of Lindisfarne, desecrating the monastery and murdering its brothers. This ferocious raid sent shock waves rippling out from Britain. When the news reached Charlemagne’s court in Aachen, Alcuin of York wrote to the king of Northumbria, deploring the fact that “the church of St Cuthbert is spattered with the blood of the priests of God, stripped of all its furnishing, exposed to the plundering of pagans.” He suggested to the king that he and his noblemen might mend their ways, starting by adopting more Christian haircuts and clothing styles. But it was too late for any of that. The Northmen had announced themselves as a major power in the western world. The next year, 794, raiders appeared on the other side of the British Isles, in the Hebrides. In 799 Vikings raided the monastery of Saint-Philibert at Noirmoutier, just to the south of the river Loire. Sixty years later Viking raids would be a painful feature of life not only in the North and Irish Seas but as far away as Lisbon, Seville, and north Africa, as Northmen tangled with Anglo-Saxons, Irish, Umayyads, and Franks. In 860 a band of Viking-descended warriors from what is now northwest Russia even sailed to Constantinople via the river Dnieper and the Black Sea, and laid the city under siege. Although exposed only to a tiny part of this, the chronicler of Noirmoutier wrote what could have been an epigram for the entire age: “The number of ships grows, the endless stream of Vikings never ceases to increase . . . the Vikings conquer everything in their path and nothing resists them.”
Dan Jones, Powers and Thrones: A New History of the Middle Ages (2021).