THE CRISIS OF the west Carolingian line in the 880s and Charles the Fat’s concerns with Germany and Italy provoked a military crisis in France, which was attacked by the Vikings. In Scandinavia the eighth century appears to have seen the rise of a dominant warrior elite at the very same time that the conquest of Frisia and Saxony brought Frankish power very sharply to their attention. The excellent ships that these coastal peoples had developed already traded with Europe, and casual raiding was always an option for a crew of thirty or so strong, fit, and armed young men. Success bred larger groups, and often substantial destruction for ordinary people on the coasts and rivers of Europe, and especially France. Very quickly, though, the Viking elite engaged with the politics of the Frankish world, often as allies of the contending Carolingian factions that fought each other after the 830s. The pain their raids inflicted upon ordinary people was, for the Frankish elite, usually a consideration secondary to the politics of the great, in which Viking leaders were so often involved. Hence, we are told that, when in 859 the Vikings were attacking northern France and Flanders,

In 867 a Viking army landed in the mouth of the Loire, perhaps seeking to exploit the tensions between the Bretons, whose land had never been fully subject to Frankish rule, and Robert the Strong, who held the March of Angers against them. Robert trapped the invaders in the church at Brissarthe and settled down to besiege them, but his men were not vigilant— a frequent weakness of medieval armies— and the Vikings burst out, killing Robert. Charles the Bald established frontier zones, Marches, like that of Robert the Strong, against all his enemies, and, as we have noted began the construction of fortified bridges to check shipborne penetration, but with only limited success.