More importantly, why are they fighting a funneled and penned enemy by climbing in with them? Where is all the siege weapons? The ballistas? The catapults? The barrels of flaming pitch? Why didn't they have this area walled off so that they bottle them in even closer together and drop anvils on them from 200 feet up? That would have to be more effective than poking them with swords and batting at them with sticks. They know exactly where the place is where these things are going to come out of, why are there no spiked pit traps? Humans are strong because they are tool users, so use the right damned tools!