Gazillions of wildlings turn up at the wall, brining all their mythical creatures with them. The Watch put up a decent battle up on the wall. All the wildlings can really do is stand near the wall while stuff is hurled down onto their heads, and wait for the gate to be breached.
Jon is put in command. That's quite a rise to power, even if he was only put their by attrition. The wildlings start to attack the gate and Jon goes all Gandalf on them: they shall not pass! Pyp sets a giant on fire with a burning keg. The mammoths run off in terror and the whole attack is routed. By this time Jon's leg hurts too much. He goes down to inspect the tunnel and everyone defending it is dead. He orders the tunnel to be sealed up. Will the wildlings get enough people through the tunnel before the main host is scared away for good? Will the brothers run out of ammo before they scare away the main host for good? It does not look good to me. I suppose if the Watch is completely destroyed Jon will be free from his vows and can go and reclaim Winterfell, for what good that will do him.
