Encyclopaedia Britannica, 11th Edition, "Bent, James" to "Bibirine" by Various

help to Hrothgar, king of the Danes, whose hall (called "Heorot") has for twelve years been rendered uninhabitable by the ravages of a devouring monster (apparently in gigantic human shape) called Grendel, a dweller in the waste, who used nightly to force an entrance and slaughter some of the inmates. Beowulf and his friends are feasted in the long-deserted Heorot. At night the Danes withdraw, leaving the strangers alone. When all but Beowulf are asleep, Grendel enters, the iron-barred doors having yielded in a moment to his hand. One of Beowulf's friends is killed; but Beowulf, unarmed, wrestles with the monster, and tears his arm from the shoulder. Grendel, though mortally wounded, breaks from the conqueror's grasp, and escapes from the hall. On the morrow, his bloodstained track is followed until it ends in a distant mere.