You've essentially described what they did later
in the book. The point of that chapter was to show hubris at work. The character being interviewed points out a number of things that were done wrong, not least of which was setting up positions at ground level rather than on roof tops or in windows where they'd be protected. As I said, in the narrative of the story the "Battle of Yonkers" is a disaster and a wake up call.
It's easy to sit back and poke holes in any unsuccessful military strategy in history; I mean what idiot tries to invade Russia in winter and what complete moron tries the same thing over a century after the last guy failed? Generals are hardly immune from stupidity.