What universal conflict lies behind his war with the danes?

It is a universal conflict of good and evil. But the conflict is between the brave, mighty, faithful warrior and the demons and dragons of hell itself. The forces of good battle the forces of evil again and again, knowing that one day they will be beaten, but at least they'll die fighting. Good in Beowulf means "strong, generous, and proud," and "evil" means "demonic creatures from the marshes." This specific battle between good and evil isn't as much about morals as it is about fate and reputation.