Athildan is 21 years old the monastery at Iona in northern Scotland will be raided a second time three years later when he's 24 years old in 806 ADCE Iona will be raiding a third time. Between 60 and 70 monks will be slaughtered by the Vikings so these are all things that Athildan in his living memory would have known about by the time he was 24. The next year 25 there are more raids on the Irish coast this about brings us up to speed to where we were when we started this story and Charlemagne is defeating the Saxons  and finding himself the new next-door neighbor to at least some of the people called the Danes