The siege of Paris from 885 to 886 is one of the more famous Viking incidents ever. Charles the fat essentially looking like he knuckles under here obviously he's not going to play well now. If you calm things down in one area they're just going to go somewhere else and it turns out the somewhere else is in Charles the fat's empire also. The only piece of magical realism by an eye witness so for example when Abbo describes a Viking climbing up a ladder getting a mixture of tar wax and oil that has been boiled poured on his head and his head explodes that's the sort of thing an eyewitness would know.