In the epic adventure of Beowulf, the monster attacks the mead hall for twelve winters. Eventually, Beowulf, a hero in his own right, who has heard of the problems of the Danes, travels across the seas to see if he can help.
On the night that Beowulf and Grendel finally face each other, the creature enters expecting to go unchallenged and have his way in the hall, unthwarted. Beowulf is something of a surprise not only because he resists, but because he is so strong. The monster manages to take the life of one unsuspecting warrior, but when he grabs Beowulf, the battle ensues. As the creature realizes he faces no ordinary man, he tries to flee, but Beowulf will not release him, and rips off Grendel's arm.
Bleeding "nigh unto death," the creature returns to his lair in the fens (swamps) to die.
in beowulf, grendel retreats to the bottom of a lake or pond with his mother after beowulf tears his arm off.