The vikings also specialized in hitting areas with litteral no defensive fortifications. The english had placed their monasteries on the rocky eastern shores to prevent them from being overrun by the locals, as the local population would occasionally attack them, but since monks generally did not fight back, attacking them was sort of like attacking a university, whose students are armed with sticks, while the vikings had axes and swords. An axe typically beats a stick, particularly if the stick is wielded by a guy who mainly does yard-work for a living.