When King Ecbert hears of Aelle's defeat, he is told the heathen army killed him near York. However, the city would have been called Eoferwic at the time.
After Ivar's idea of using terrain to defeat a larger enemy (Aethelwulf's) proves to be successful, Bjorn calls Ivar a 'genius'. The term was however coined in mid 17th century, about 800 years later.