That’s the second fascinating history link I’ve found on the straightdope today.
You can see some of the self delusion in the Japanese report when it says stuff like: “The Americans put great faith in their superior artillery, but we believe we can counter the enemy’s advantage with our superior bayonet skills.” That sounds like something a general would have said during the American Civil War right before he went on to lead his men to a spectacular defeat.
I do find it oddly interesting that both the Americans and the Japanese admitted that they thought the opposing side had sweet hand grenade skills.