Ragnar Lodbrok's sons Sigurd Snake-in-the-Eye, Björn Ironside and Hvitserk had raided in France and after Björn had gone home to Sweden, his brothers were attacked by emperor Arnulf of Carinthia.
In the battle 100,000 Danes and Norwegians fell, including Sigurd Snake-in-the-Eye and king Guðrøðr.
Helgi escaped from the battle with Sigurd Snake-in-the-Eye's banner, sword and shield.
Since the next king, Harthacnut, was still too young to rule, Helgi stayed in Denmark as its regent.
There, Helgi married Harthacanute's twin sister, also named Aslaug, and they had the son Sigurd Hart.