cheapcakeripper:

Worst day of king Aelle’s life aka why there’s no battle in 4×18.

According to the sagas, the ‘great heathen army’ didn’t defeat Aelle when it arrived.  They agreed to a truce in which Ivar the Boneless asked for as much land as he could cover in an Ox’s hide in exchange for not attacking.  Aelle obviously thought he’d got off incredibly lightly, but Ivar then cut the hide into fine strands that he could cover an entire town with (either York or London, depending on the source).

The Vikings then just waited a year then attacked Aelle again anyway and doing the whole blood eagle thing.  It’s unknown whether he ever got an autograph.