What does Corlath explain about his plans for the army, what does Harry ask about, what is Corlath's response and how does Harry feel about his response?

Corlath explains that the army plans to head to the largest gap in the mountains. Harry asks Corlath about another gap in the mountains, where the Northerners could send a smaller army to come from behind, and notes that if warned, the Outlanders could likely hold the gap. Corlath angrily notes that they were warned. After a brief argument, Harry angrily thinks that Corlath's pride will likely lead to their downfall.