Mormon tells us who the captain of Noah is because he wants us to know that he is one of the most trusted by Moroni. As the one who captained the surprise force in the earlier battle, he is clearly someone to whom Moroni entrusted a major tactical portion of a battle that had to work correctly. This is further indication that Moroni correctly interpreted the Lamanite action at Ammonihah. We have Mormon’s statement that the by-passing of Ammonihah and the march on Noah was just what Moroni wanted, and the presence of such an important general in Noah (as opposed to Ammonihah) indicates that this truly was Moroni’s plan. Not only were the fortifications better at Noah, but the leadership was the best Moroni could concentrate in a single city.