sentences:  "Heimskringla" specifies that Haakon owed his success in large part to Sigurd, earl of Lade.Determining the date and length of Eric's reign (before and after his father's death) is a challenging and perhaps impossible task based on the confused chronology of our late sources.It is also unfortunate that no contemporary or even near contemporary record survives for Eric's short-lived rule in Norway, if it is historical at all.