The Norse Army

Earls edwin and morcar marched towards the norse army. Why would they do this? It sounds like there was more than a little dissension in northumbria, and that many were siding with hadrata or at least submitting to him. They might have felt like they had no other choice. If the norse continued pillaging the lands along the euse and all around york, that could have undermined what little support the brothers still had among the northumbrian nobility.