When you attack the Hobgoblin leader it turns all goblins hostile. Plus in the room where he is, there is a drum that the goblins use to summon more goblins into the room.
What is spell V and S btw? What are you attacking that "nothing registered"? Are you attacking him? Did you speak to him first, and combat was initiated through the conversation? Did you attack him out of cutscene?
This is not "hard" mode either, if you learn how to play the game, this combat is super easy.
