The fight was still going on all around, and the acromantulas were beginning to swarm the battlefield. In the distance, Harry and some Order members were beating back the Dementors with their own phalanx of Patronuses. They were about to be outflanked and overrun by the giant spiders when the House-Elves ran into the field, armed with knives and whatever they could get a hold of to slaughter the incoming arachnids.