Holy crap. Any of these guys making so many speeches a day without prompters can make a mistake. His mistake doesn’t show illiteracy; it’s just like a spoken typo. 7/11 is a thing and so is 9/11.
He didn’t pronounce corpsmen as corpsemen. He didn’t say he sees so many fallen heroes in the audience.
Such a mistake doesn’t happen to Lying Hillary. She carries prompters everywhere.