What do Beowulf's battles with Grendel, Grendel's mother, and the dragon have in common?

In all of these battles, Beowulf is the stereotypical warrior.  He sets out alone, and he relies mostly on his brute strength, as opposed to his wisdom, in order to accomplish his tasks.  Consider his battle with Grendel - he holds onto Grendel with a vise-like grip until the monster's arm is ripped from his body.  However, Beowulf is compassionate and he is intelligent.  He sets out on all of these battles not for glory but to help others, to serve his people.  The biggest difference between the battles is in the last one, with the dragon.  Here he allows another, Wiglaf, to come to his aid, recognizing that he is too old to take care of the situation himself.