Well, it's revisionist history at it's worst.
The movie suggests that U.S. servicemen didn't understand why they were fighting the Nazis, couldn't explain why they were being killed by the thousands in Europe. They we're on some unexplicable errand, that's all.
It's a major swipe at a whole generation of servicemen who during WWII knew very well what was at stake and why their sacrifice was necessary.
That Spielberg should turn his considerable talents in such a disrespectful direction is beyond me.