Again, it is worth pausing to reflect on this. Less than a century earlier, perhaps a few dozen men ran up a beach to burn the monastery at Lindisfarne in an attack that was probably over in less than a day. At Paris, a fleet of thousands of Vikings, in hundreds of ships, besieged one of the greatest cities of Europe for a year, and fought pitched battles with the best soldiers the Empire could field. The speed and scale of the escalation is breathtaking.

