Why are the goblins scared of the two swords?

They are scared of the swords because their ancestores have been slaughtered by these to swords and the head goblin was just killed and the lower goblins don't want to be killed but they got mad and chased the 13 dwarfs, the hobbit, and the wizard. when the goblins caught up they caught all of the dwarfs and the wizard but not the hobbit and then he found a ring.